题目

阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。I can still remember the afternoon when we climbed the mountain as if it were yesterday.It was a sunny day. Eager to spend some time outside, I went up the mountain with my uncle. The mountain was hard 【1】(climb) and had tough rocks and streams on it. In the end, 【2】 (exhaust) and hot, I couldn’t go any further. So we went back down the mountain in the end.On the way back down, my uncle asked me a question, 【3】 left me speechless for a second: “What’s your dream, young lady?”“I h一个物体只受F1和F2两个力的作用，这两个力的三要素完全相同，则此物体所受的合力是（ ）A. 0 B. F1 -F2 C. F1 + F2 D. 无法确定