—Will you give me a hand? I have some trouble_______ the scientific problem.

—Don't worry. I'll try my best to help you _______.

A．solving; in five minutes

B．to solve; in five-minute

C．to solve; after five minutes

D．solving; after five-minutes

装卸桥的一个支腿与主梁（），称为挠性支腿，只承受垂直载荷。

A.焊接

B.螺栓联结

C.铆接

D.铰接