4.15There’s plenty of time, so you worry about it.

A. 　 give up

B. 　 giving up

C. 　 to give up

D. 　 having given up

A. 　 on

B. 　 for

C. 　 with

D. 　to

A. 　危害人体的电磁辐射

B. 　电磁辐射与环保

C. 　电磁辐射的热作用和非热作用

D. 　无处不在的电磁辐射

A. 　 had begun

B. 　 will begin

C. 　 has begun

D. 　 begins

A. 　 has woken up

B. 　 is waking up

C. 　 will wake up

D. 　 wakes up

A. 　 bright

B. 　 weak

C. 　 soft

D. 　 natural

A. 　 aiming

B. 　 looking

C. 　 waving

D. 　 pointing