4.17A few days ago I visited a friend of ()and that day I learned a valuable lesson.

3.14 David has decided ()football at the end of this season.

A. 　 give up

B. 　 giving up

C. 　 to give up

D. 　 having given up

1.24. A. That B. What C. Whom D. Who

4.19Family members worked hard ()sure that they had enough food.

A. 　 making

B. 　 make

C. 　 made

D. 　 to make

3.21 通读下面的短文,掌握其大意。然后,从每小题的四个选项中选出最佳选项。
Over the summer, my family took a trip to Iceland to see the natural beauty of it. Little did I (21) I would wake up one morning to have my eyes swelled up (肿胀)like balloons! I was frightened. So many questions were( 22 )through my head. Am I allergic(过敏的)to something? Was there some Icelandic disease that I( 23 )? The only help I received was some allergy medicine( 24 )a clinic nearby. Nothing was working.
When the trip was over, I went to see my doctor. She gave me eye drops, but clearly they weren’t worth the time or (25) and the swelling got worse and worse.

A. 　know

B. 　 doubt

C. 　 insist

D. 　 fear

3.13The letters () on your desk yesterday, but you didn’t read them at all.

A. 　 were put

B. 　 being put

C. 　 put

D. 　 have put

3.16 My brother worked than any other member in his team and got the first prize.

A. 　 hard

B. 　 harder

C. 　 hardest

D. 　 hardly

1.17 Everything changed ()quickly that I almost had no time to think.

A. 　 such

B. 　 how

C. 　 as

D. 　 so

4.7阅读下列文字
电磁波已成为一种新的污染源。它看不见、摸不着,穿透力强,充斥着整个空间,令人防不胜防。
电磁污染源主要包括两大类,即自然型电磁污染源与人工型电磁污染源。前者来源于某些自然现象,以天电所产生的电磁污染最为突出。后者产生于人工制造的若干系统(如高压系统)、电子设备与电气装置。
人体处在一定强度的电磁场下,会吸收辐射能量,发生生物学作用,包括热作用和非热作用。
所谓热作用,就是高频电磁波对生物机体细胞的“加热”作用。人体接受电磁辐射后,体内的分子会受到磁场的影响而重新排列,在重排过程中,分子间相互碰撞、摩擦而产生热能,引起热作用。人体内电解质溶液的离子因受到电场的作用而发生移动(传导电流),也能使电解质变热。另外,由于人体内某些成分(如体液等)为导体,还可产生局部性感应涡流,也会产生热。如果人体吸收的辐射能太多,靠体温的调节无法把热量散发出去,就会引起体温升高,进而引发各种病症。由于电磁波是穿透生物表层直接对内部组织“加热”,往往机体表面看不出什么,而内部组织却已严重“烧伤”。
至于电磁波的非热作用问题,正在进一步研究之中,一般认为是低频波产生的影响。人体被电磁波辐射后,体体温并未明显升高,但已经干扰了人体的固有微弱电磁场,造成细胞内遗传基因发生畸形突变,进而诱发白血病和肿瘤,还会引发胚胎染色体改变,导致婴儿的畸形或孕妇的自然流产。
鉴于电磁辐射对人体的危害,联合国人类环境会议已将防治电磁辐射污染列为环境保护项目。
属于自然型电磁污染源的一项是( )

A. 　家用电器

B. 　高压、超高压系统

C. 　雷雨天气

D. 　无线电广播通讯设备

5.24.

A. 　 hardly

B. 　 almost

C. 　 much

D. 　 far

3.19 —Do you mind if I open the window?
---().

A. 　Yes, please

B. 　 No, go ahead

C. 　 No, please don’t

D. 　 Yes, you’d better do