钢筋保护层厚度检验时，对选定的板类构件，应抽取不少于（）根纵向钢筋的保护层厚度进行检验。
A.10
B.8
C.6
D.7
参考答案：C
Please read every sentence . The more ______ you are, the fewer mistakes you'll make. [ ]
A. carefully; carefully
B. careful; careful.
C. carefully; careful
若要查找最近 20 天之内参加工作的职工记录，查询准则为_________。
