If you go out to the fields at night in spring or summer，you can hear frogs singing     1     (happy) here and there. It seems as if they were performing a field group singing.

The frog is a good and useful animal that     2     (benefit) human beings. They can catch fast-moving insects. Each frog eats a large number of pests (害虫) that are     3     (harm) to crops. This little creature is considered     4     “the natural enemy of pests”.

But now frogs are getting     5     (few) than before. This is because they are killed and put on the table as a delicious dish by their chief enemy, human beings. It is a shameless and cruel act, isn’t it?

The reason for the rapid reduction (急剧减少) of frogs is that famers use insect killer to kill pests and frogs get killed as     6     result of drinking poisoned water while     7     (eat) poison- killed insects.

Something must be done as soon as possible     8     (save) frogs. If we don’t punish those     9     sell and kill frogs to make money, then one day all of us will     10     (punish) by nature for failing to keep them.

As an attractive city in the Netherlands, Amsterdam is one of the most bicycle-friendly    1    (city) in the world having over 800, 000 bikes in the capital. By comparison, the city has a population of only 750, 000 less than the number of bikes. According to a survey    2    (make) 5 years ago 490, 000 people used bicycles everyday.

Up to now, people in Amsterdam    3    (enjoy) the convenience of cycling for decades. The city has special facilities for cyclists,    4    can be used for free. Compared with other transportation in the city, bikes are    5    (clean) and less expensive while also    6    (offer) health benefits.    7    reason for bicycle riding is that bicycle traffic is    8    (relative) safe. Amsterdammers ride a wide    9    (vary) of bicycles. Many tourists also discover Amsterdam by bike, which is    10    typical Dutch way.