— _________ do you have PE lessons?

—Three times a week. [ ]

A. How long

B. How soon

C. How many

D. How often

轴心受拉和小偏心受拉杆件中的钢筋接头，不应绑接。普通混凝土中直径大于（）mm的钢筋，应采用焊接。

A.10

B.15

C.20

D.25