You use conditionalclauses to talk about a possible situation and its results.
条件从句用以表示某种可能的情形及结果。
2
The auxiliary forms of need are used primarily in present-tense questions, negations, and conditionalclauses.
Need的助动词形式主要用于现在时态的疑问句、否定句和条件句中。
3
Formal words are used. The language accuracy is required. Active voice, present tense, direct expression and conditionalclauses are more frequently used.