高空施焊时必须使用标准的防火(),带头罩。
A.焊具
B.安全带
C.工作服
D.工具
参考答案:B
He won't telephone us until he back. [ ]
A. come
B. comes
C. came
D. will come
阅读下面的程序段,执行上面的三重循环后,a的值为 ______ 。 For i=1 To 3For j=1 To i For k=j To 4 a=a+1 Next kNext j Next i
A.9
B.24
C.14
D.20