热泵空调器制冷时出现高压低,低压高,有可能是()。
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The cylinder covers and the liners are bolted together by means of studs () the cylinder frames.
A. screwing into
B. being screw on
C. to screw on
D. screwed into
黄油是从牛油中分离出来的高级脂肪制品()
A. 正确
B. 错误
SSL协议是通过什么来验证通信双方身份的?()
A. 密钥
B. 证书
C. 500
D. 509