In English conditional sentences, the condition clause (protasis) is a dependent clause, most commonly introduced by the conjunction if. Other conjunctions or equivalent expressions may also be used, such as unless (meaning if...not), provided (that) , providing (that) and as long as.irst conditional or conditional I refers to a pattern used in predictive conditional sentences, i.e. those that concern consequences of a probable future event (see Types of conditional sentence).
Weathering and erosion. Weathering is the process where rock is dissolved, worn away or broken down into smaller and smaller pieces. There are mechanical, chemical and organic weathering processes. Organic weathering happens when plants break up rocks with their growing roots or plant acids help dissolve rock.
CHAPTER 11: WATER AND ENERGY Physical weathering Weathering How is a large mountain broken down into tiny grai ns of sand? The process of breaking down rock is called weathering (Figure 11.3). Physical weathering Physical forces may break or chip rocks into smaller pieces. This process is called physical weathering. Physical weathering may break large blocks loose or chip away tiny grains, one at a time. Liquid water Liquid water is a physical weathering agent. Rocks break up