对于如下补充业务,会产生相应的补充业务话()
A.呼叫转移话单
B.呼叫保持和等待话单
C.多方通话话单
D.呼叫闭锁类话单
参考答案:A, B, C
To our disappointment, the trip we had been looking forward to ________ in the pouring rain.[ ]
A. starting
B. start
C. to start
D. started
根据下表中的已知条件,判断苏氨酸的密码子是( )。
A.TGUB.UGAC.ACUD.UCU