public static void main ( String [ ] args ) throws IOException {
  BufferedReader f = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  StringTokenizer st = new StringTokenizer ( f . readLine ( ) ) ;
  int t = Integer . parseInt ( st . nextToken ( ) ) ;
  while ( t > 0 ) {
    t -- ;
    int n = Integer . parseInt ( f . readLine ( ) ) ;
    int plays = 0 ;
    int clears = 0 ;
    boolean yes = true ;
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      st = new StringTokenizer ( f . readLine ( ) ) ;
      int nextPlays = Integer . parseInt ( st . nextToken ( ) ) ;
      int nextClears = Integer . parseInt ( st . nextToken ( ) ) ;
      if ( nextPlays - plays < nextClears - clears ) {
        yes = false ;
      }
      if ( nextPlays < plays || nextClears < clears ) {
        yes = false ;
      }
      plays = nextPlays ;
      clears = nextClears ;
    }
    if ( yes ) System . out . println ( "YES" ) ;
    else System . out . println ( "NO" ) ;
  }
}

public static void main ( String [ ] args ) throws IOException { BufferedReader f = new BufferedReader ( new InputStreamReader ( System . in ) ) ; StringTokenizer st = new StringTokenizer ( f . readLine ( ) ) ; int t = Integer . parseInt ( st . nextToken ( ) ) ; while ( t > 0 ) { t -- ; int n = Integer . parseInt ( f . readLine ( ) ) ; int plays = 0 ; int clears = 0 ; boolean yes = true ; for ( int i = 0 ; i < n ; i ++ ) { st = new StringTokenizer ( f . readLine ( ) ) ; int nextPlays = Integer . parseInt ( st . nextToken ( ) ) ; int nextClears = Integer . parseInt ( st . nextToken ( ) ) ; if ( nextPlays - plays < nextClears - clears ) { yes = false ; } if ( nextPlays < plays || nextClears < clears ) { yes = false ; } plays = nextPlays ; clears = nextClears ; } if ( yes ) System . out . println ( " YES " ) ; else System . out . println ( " NO " ) ; } }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_identifier)) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (expression_statement (update_expression (identifier))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (boolean_type) declarator: (variable_declarator name: (identifier) value: (true))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (identifier) right: (object_creation_expression type: (type_identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (binary_expression left: (identifier) right: (identifier)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (false))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (binary_expression left: (identifier) right: (identifier)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (false))))) (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (identifier))))) (if_statement condition: (parenthesized_expression (identifier)) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) alternative: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))))))))