下列元素中,属于人体必需微量元素的是()。
A.钙
B.铁
C.钾
D.钠
E.氯
参考答案:B
解析:人体必需的微量元素是铜、钴、铬、铁、氟、碘、锰、钼、硒和锌。
起重机静力试验试验目的是检查()。
A.起重能力
B.起重设备的总强度
C.制动器的动作
D.绳索强度
E.支撑机构强度
用所给动词的正确形式填空。
1. My mother asks me if I _____ (go) to the park.
2. Why is Lily_____(sit) under the tree? It's time to have class.
3. My father _____(mend) my bike while my mother was washing clothes.
4.Tom _____(die) ten years ago, he has been dead for ten years.
5.I will tell him the good news as soon as he_____(come) back.
6.Lucy and Lily missed _____(watch) the wonderful film.