Don't get yourself into ___ of drinking.

A. habit  B. job   C. the job    D. the habit

It rained nonstop for ten days , completely       our holiday.

   A. to ruin        B. ruined       C. having ruined    D. ruining

I’m told that languagepractising．com is a free website ______learners can not just learn

various languages but also chat online．

A．where      B．which      C．that D．what

Read the passage and correct the mistakes, ______．

A．if not           B．if any       C．if ever     D．if never

＿＿＿with the present global difficult economic situation, many people don’t dare to invest money in stock market any more.

       A．To face  B．Having faced   C．Faced     D．Facing

All of the guests         by 9 o’clock , but the host        until 15 minutes later .

   A．a(chǎn)rrived ; didn’t turn up    B．had arrived ; didn’t turn up

C．a(chǎn)rrived ; hadn’t turned up      D．had arrived; hadn’t turned up

   Most of us think that when we step under a shower we’re getting clean．We are, but we’re also giving a home to lots of tiny little creatures we didn’t even know about．

   A showerhead carries thousands of bacteria (細菌) called Mycobacterium．These can cause problems like coughs and tiredness, and a general feeling of poorliness (身體不舒服)．When you turn on the water, the bacteria go from the showerhead onto and into your body．

   This is a finding of Norman R．Pace and his team at the University of Colorado, in the US．The scientists investigated bacteria in all kinds of human environment, including showers．

   Pace's team looked at 45 showerheads in nine American cities．They discovered that 30 percent of them had large amounts of flying Mycobacterium．

   But Pace said that they pose few threats to the health．Only those with a frail (脆弱的) immune (免疫的) system might need to worry．

   He told the New York Times that the bactertia are not as unpleasant as might be thought．He said that having a shower is no more dangerous than anything else we do in the morning．

   But for those who feel sick about the idea of all those microorganisms (微生物), he had some advice．

   Let the water run for 30 seconds before getting into the shower．Why? The number of bacteria is smaller than when the water is just turned on．If that seems like a waste of water, he added that you could also change your showerhead every few months．

   But Pace had good news too．He has also been testing the air in US subways．Apart from iron particles (粒子), which are ground off the track by the wheels of trains, subway air is fresh．The reason is that a train’s movement pumps fresh outdoor air into the tunnels(隧道)．

   Pace explained that he wanted to understand the natural microbial(微生物的) environments of public places．This kind of knowledge might help detect the microbes to be used in a bioterrorist (生物恐怖分子) attack．

49．According to the finding of Norman R．Pace, after taking a shower, we might ______．

       A．get much dirtier                 B．be covered by bacteria

       C．get a frail immune system      D．catch a cough or feel tired

50．Pace’s research into showers shows that ______．

       A．there is no reason to fear microorganism

       B．shower water contains much less bacteria after being left to run for 30 second

       C．having a shower in the morning is more dangerous than at other time

       D．of 45 showerheads surveyed in nine cities, 30 carried large amounts of Mycobacterium

51．According to the research of Pace’s team, which of the following contributes to fresh air in US subways?

       A．Train wheels．                B．Iron particles．

       C．The movement of the trains． D．Air conditioners on the trains．

52．The word “detect” in the last paragraph probably means “______”．

       A．to discover      B．to protect        C．to make   D．to prevent

The old houses are being pulled down to ____ a new office block.

   A. supply with    B. make use of    C. make room for     D. take the place of

Because of the poor harvest, wheat prices have _____ in the last six months.

　　A. added    B. jumped    C. amounted    D. developed

After a short holiday, he _____ himself once more to his studies.

　　A. applied    B. converted    C. engaged    D. exerted