Never _______ protecting our earth. It is the only nice planet for us to live on.

A．leave for

B．learn about

C．give up

D．look up

石决明的作用是（）

A.平肝潜阳，清肝明目

B.重镇安神，潜阳补阴

C.重镇安神，软坚散结

D.平肝潜阳，重镇降逆，凉血止血

E.平肝疏肝，祛风明目