阅读下面短文,从A,B,C,D中选出一个能填入短文中相应空白处的最佳选项.

阅读下面短文,从A,B,C,D中选出一个能填入短文中相应空白处的最佳选项.
Sometimes very good things have problems．Mobile phones are helpful but they 36 a lot of pollution and damage our health．If you read these things．you won't use your phones．
First．they make pollution．When we make phones we use a lot of energy and a lot of chemicals．Mobile phone batteries are very 37 for the environment,and people change phones often-every day we throw away thousands and thousands．
38 , I want to talk about cheating．Some students try to use mobile phones in exams to get help 39 the questions．This is very bad and a good reason not to allow mobile phones into schools, but they are small so it is difficult to see them．
Third,mobile phones are a waster of 40 ．Young people spend too much on making calls and sending messages．They are also a waster of time．Many of the messages we send and receive are not useful．We may even receive a lot of e-mail we do not want．The world is full of 41 messages．
Fourth,when we use mobile phones our health is in 42 ．If you hold a phone next to your head,a lot of microwaves(电波)enter it and hurt your brain．43 you use a phone in a petrol station(汽油站),it may start a fire．Some people use their phones when they are driving cars．They don't look at the road and it is 44 for them to have an accident．
Fifth,mobile phones make people angry．In restaurants,concerts and cinemas you hear phones all the time．This is serious 45 pollution．With a phone you have no peace．Everyone knows where you are and can talk to you at any time．People may sometimes listen to our calls．
36．A．help B．make C．grow D．let
37．A．bad B．good C.helpful D．useful
38．A．And B．Next C．Then D．Second
39．A．doing B．answering C．1earning D．making
40．A．time B．phones C．money D．messages
41．A．useless B．helpful C．useful D．helpless
42．A．safety B．safe C．dangerous D．danger
43．A．What B．Where C．If D．Why
44．A．safely B．easy C．hard D．impossible
45．A．air B．water C．noise D．1ight