Audio 11. Many smaller animals are absolutely necessary for....................______ .................2. Bumble bees are more popular than ...................______ ..................3. Bees are important because they help plants to ................______ .....................4. In the U.S., bees seem to be in ........................______ ........................5. All insects and “creepy craw lies” keep the whole system......................______ ...............
查看答案
Why was the usefulness of Dr Cullen’s cooling process missed?___
A. People lacked imagination.
B. It took too long to develop.
C. There was an element of risk.
What prompted John Gorrie to make his machine?___
A. the onset of personal ill-health
B. unreliable access to natural ice
C. the possibility of becoming rich
Why were the early fridges phased out?___
A. They kept breaking down.
B. They were costly.
C. They were dangerous.
What was the drawback of the new chemicals used?___
A. Their supply was becoming limited.
B. They caused ecological damage.
C. They only had a short shelf-life.
微信支付 
支付宝支付