二级单位负责编制并审批本单位安全附件的修理、改造方案及校验、更新计划，（）负责组织实施。
A.机动设备处
B.二级单位
C.车间
D.施工单位
参考答案：B
根据句意，写出括号内所给单词的适当形式。
1. At present people like to eat _________(health) food and do more exercise.
2. The three _________(spaceman) of the spaceship were warmly welcomed in Hongkong.
3. He has had a bad toothache. He must be at the _________(dentist) at the moment.
4. Daniel's mother has devoted _________(she) to the teaching of Home Economics.
5.He is very happy because tomorrow is his _________(九十) birthday
设f(x)在区间[a，b]上连续，在(a，b)内可导，f’(x)＞0，存在。证明： (Ⅰ) 在(a，b)内有f(x)＞0； (Ⅱ) 存在ξ∈r(a，b)，使得 (Ⅲ) 存在η∈(a，b)，使得
