双吊杆作业时应（） ①避免突然转向； ②避免急刹车； ③避免用吊钩拖拉货物； ④避免吊货索摩擦； ⑤异常情况停顿检查。
A. ②③④⑤
B. ①③④⑤
C. ①②④⑤
D. ①②③④
查看答案
There are 3 steps to confirm whether a range of IP address can be summarized. When of thefollowing is used in each of these 3 steps？（）
A. The first number in the contiguous block of addresses
B. The last number in the contiguous block of addresses
C. The size of the contiguous block of addresses
D. The subnet mask of the original network addre
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