对楼板为现浇板的框架结构,中框架梁的截面形式是()。
参考答案:T形
There are a great many books in the store, _____ some are useful to us. [ ]
A. of them
B. in which
C. of which
D. in them
用折射角45°的探头,一次波法探测厚度为100mm的试件,若有机玻璃斜楔中的声程为15mm,则最大测距相当钢中纵波声程()。