用 electric, electricity, electrical及 electronic填空

1.Turn off the computer when you don't use it. Don't waste  __   .

2. His father is an          engineer.

3. Do you know who invented the          light?

4. Nowadays most young people prefer to send          mails rather than write letters.

下列哪种肿瘤与遗传因素关系密切（）。

A.胃癌

B.肺癌

C.肾癌

D.黑色素瘤

E.视网膜母细胞瘤