I am in our school team and we are going to play ________ another school next week.A. on B. against C. of D. across 答案:【答案】B【解析】句意:我在我们的学校队里,下周我们将与另外一个学校比赛。此句考查常用介词的辨析。分析句子,结合选项,推测意思是我在我们的学校队里,下周我们将与另外一个学校比赛。根据固定短语play against与…对抗,比赛。可知,此空故填against,故选B。根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
It’s summertime-time once again for mosquitoes to make
their appearance. And once they appear, mosquitoes are a total pain. They land
on you, bite you, suck out some blood and leave behind an itchy welt(发痒的红肿).
1 Female mosquitoes must find blood in order to
reproduce, so mosquitoes come equipped with finely tuned sensors to help them
locate the blood they need.
Mosquitoes’ weapons
Mosquitoes have perfected three different types of
sensors. First, mosquitoes can sense several different chemicals. Mosquitoes
can smell carbon dioxide and lactic acid(乳酸)up to 100
feet away. 2
Second, mosquitoes have very good eyesight. If you are
wearing clothing that contrasts with the background, and if you move while
wearing that clothing, mosquitoes can see you. It’s a good bet that anything
moving is alive, and therefore full of blood.
Finally, mosquitoes come equipped with temperature
sensors, so they can find warm-blood mammals and birds very easily.
3 The female mosquito sticks her proboscis(喙)into you. She sucks about five microliters of your
blood into her abdomen.
After she has bitten you, some saliva(唾液)remains in the wound. 4 The
area swells and you tich. Eventually, the selling goes away, but the itch
remains until your immune cells break down the saliva proteins.
Our defense methods
Because mosquitoes are both a nuisance(讨厌的东西) and a danger, people prefer to stay away from mosquitoes.
One way to do that is to use a chemical called DEET, which seems to black a
mosquito’s chemical sensors. 5 In some cities there
are even trucks that drive around town to spray for mosquitoes. Finally there
are to traps. The most popular traps turn propane(丙烷) into carbon dioxide and warmth to attract mosquitoes.
Over time, by catching large numbers of mosquitoes, these traps can cause the
collapse of the mosquito population in the area.
A.Another way
to control mosquitoes is with insecticides(杀虫剂) that
kill them.
B.How
mosquitoes work is unknown to most of us.
C.Once a
mosquito lands on you, it is time to bite.
D.Some bites of
mosquitoes are more serious than you thought.
E. Mammals and birds give off these gases as part
of their normal breathing.
F. The proteins from the saliva create an immune
response from your body.
G. But if you ignore the fact that mosquitoes are so
annoying they really are amazing.