— Can you guess _______ the new Nike sports shoes?

—Yes, maybe he asked his grandpa for the money, I think.

A．how he paid for

B．where he bought

C．when he paid for

D．why he bought

在进行坡口对接焊时，坡口状态应在（）情况下才允许施焊。

A.只要装配完成就可以进行施焊

B.把坡口清理一下，没有杂物就可进行施焊

C.把坡口打磨光顺，没有杂物，并符合工艺要求才能进行施焊