What is this news mainly about
A. The safety of air ambulances.
B. The safety of rescue workers.
C. Air ambulance accidents since 1978.
D. Helicopter crashes since 2000.
查看答案
锅炉折焰角的主要作用是（ ）。
A. 凝渣
B. 稳定燃烧
C. 改善传热
D. 防止管排磨损
In Arkwright's view, what property should a spinning machine have
A. It should not require a skilled operator to run it.
B. It should be powered by electricity.
C. It should be able to produce 128 threads at one time.
D. It should be operated by han
What happened to one of the guys in the competition
A. He was badly injured.
B. He was seasick.
C. He fell off his bike.
D. He lost his bik
What do the man and the woman talk about
A book on birds.
B. Species of birds.
C. A man chasing birds.
D. Activities of watching birds.
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