数控机床机械结构特点是（）。①高刚度②高抗振性③低热变形④高的进给平稳性

A、①③

B、①②④

C、①②③

D、①②③④

We worked hard to（）a barren landscape into an area of beautiful pastureland.

A.transfer

B.transform

C.transmit

D.transport