设函数y=tan x2，则
______。
参考答案：
— Was your father at home last night?
— No, my father wasn't at home. He ______ to help to send the old man to hospital. [ ]
A．asked
B．was asked
C．was asking
D．had asked
管材的规格用（）×壁厚表示。
A、内径
B、外径
C、中径
D、公称直径
______。
______。