多项选择题

关于受迫振动，下面说法正确的是（） A.
是在一恒力作用下的振动 B.
振动频率可能大于或小于系统的固有频率 C.
振动频率一定等于系统的固有频率 D.
振动频率一定等于驱动力的频率

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单项选择题

请判断下面单词的音节个数cable音标[ ‘keibl]释义n.缆，索;电缆;电报 A.
1 B.
2 C.
3 D.
4 E.
5

The “______” pattern also reflect in “The Road Not Taken”---a traveler made a choice between two roads in the wood, went through an adventure about whether it was a good or bad one and recollected in an old age with an initiated sigh.

答案： quest