站车有关工种应紧密配合,组织旅客按照车厢号在标明()处排队等待,有序乘降。
A. 车门位置
B. 列车位置
C. 车厢位置
D. 等车位置
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当晶体管处于放大状态时,其特征是:发射结处于()偏置,集电结处于反向偏置。
A. 正向
B. 反向
C. 左向
D. 右向
某急性心梗病人发病14小时后,进行LD同工酶检查AMI时,LD最早出现变化的间时为()
A. 2~4小时
B. 4~8小时
C. 8~12小时
D. 12~24小时
E. 24小时以上
Evaluate the CREATE TABLE statement: CREATE TABLE products (product_id NUMBER (6) CONSTRAINT prod_id_pk PRIMARY KEY, product_name VARCHAR2 (15)); Which statement is true regarding the PROD_ID_PK constraint?()
A. It would be created only if a unique index is manually created first.
B. It would be created and would use an automatically created unique index.
C. It would be created and would use an automatically created nonunique index.
D. It would be created and remains in a disabled state because no index is specified in the command.
恶意呼叫识别(MCI):移动用户可要求在网络中识别并记录一个不希望的呼入源()
A. 正确
B. 错误