问题
单项选择题
以下（）形状叶片风机效率较高。
A、径向叶片
B、后弯叶片
C、翼型叶片
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
以下（）形状叶片风机效率较高。
A、径向叶片
B、后弯叶片
C、翼型叶片
参考答案：C
| 完形填空。 | ||||
| What do you know about the sea? Everybody knows that the sea 1 beautiful when the sun is shining 2 it. But it becomes very terrible when there is a strong wind. If you study the map of the world, you'll  3 that about three quarters of the world is the sea.Have you ever been at sea? The sea is very deep. In some places the sea is much deeper. The 4 mountain in the world is about 9 kilometers high 5 the deepest place of the sea is 6 11 kilometres deep. The sea can be very cold. At the top of the sea the water may be 7 . But if you go down it becomes colder and colder. In most places of the sea, there are lots of 8 and plants. Some live near the top of the sea. Others live deep down. You know the sea water is salty. The water of the Dead sea is very salty. It's so salty that fish 9 live in it. 10 a strange sea! | ||||
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