Question

Beneath each of the following sentences there are four choices marked A, B, Cand D. Choose the one answer that best completes the sentence.Small sailboats can easily turn over in the water ______ they are not managed carefully.

1. A.
   though
2. B.
   before
3. C.
   until
4. D.
   if

Answer 1

D
思路分析：句意為：小航船如果操作不小心很容易在水里翻了。由此知前后兩句是主從條件句。though引導(dǎo)讓步狀語(yǔ)從句；before和until都引導(dǎo)時(shí)間狀語(yǔ)從句。
【點(diǎn)評(píng)】本題考查狀語(yǔ)從句，難度偏適中。