船舶需进行明火作业时,其危险区域的开敞甲板,从作业点向首尾延伸,以船舶宽度为界,向下至平台或甲板,向上()米的柱形空间为作业环境考查区域.
A.2
B.3
C.4
参考答案:A
词汇运用。
1. Amy has vegetables every day. But now she _________ (eat) a hamburger.
2. If you want to _________ (health), have the food on these _________ (shelf).
3. We all would like to make friends with the boy _________ (call) Tom.
4. The _________ (two) lesson is not difficult to understand.
5. My friend doesn't like carrots. So he never has _________. (some)
6. There are _________ (little) than two kilos of salt in the kitchen.
7. It's important _________ (have) a right diet and lifestyle.
8. I will tell you the size of my _________ (foot), then you can buy a pair of shoes for me.
9. The city is really modern, but it also has a lot of air _________ (pollution).
交-交变频装置输出频率受限制,最高频率不超过电网频率的(),所以通常只适用于低速大功率拖动系统。
A、3/4
B、1/5
C、1/2
D、2/3