By the time some scientists ____ the lost towns, they ____ an awesome historical site.

A．had found, had found

B．found, found

C．found, had found

D．had found, found

Such good use has been ________ his spare time ________ his English has improved a lot.[ ]

A. made of；as  

B. made of；that

C. made in；that  

D. made from；as