题目

Trees are very important. We can't ________.A. cut them down B. cut it down C. cut down them D. cut down it 答案：【答案】A【解析】句意：树木非常重要。我们不能砍伐它们。cut down为动副词组，代词放在中间，trees为名词复数形式，需要用代词them来替代，故答案为A。It took us much time ________ the mountain.A. climb B. climbed C. to climb D. to climbing