题目

Only when _____ the painting _____ decide whether the painting is worth buying.A. he sees, he canB. does he see, can he C. he sees, can heD. sees he, he can   答案：C  only引导的状语在句首，主句要部分倒装。南昆铁路是我国西南出海大通道，它经过的地形区是（　　） A、青藏高原B、四川盆地C、云贵高原D、山东丘陵