Wang Ming ___ English since he went to middle school.
A. learns
B. has been learning
C. has learnt
D. is learning
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When mother came in, the twins ___ a talk.
A. were having
B. have had
C. had have
D. had
I won't go to bed until I ___ the job.
A. have done
B. had done
C. will do
D. do
机构运动简图与( )无关。
A. 构件数目
B. 运动副数目、类型
C. 运动副的相对位置
D. 构件和运动副的结构
机构运动简图和机构运动示意图含义相同。
A. 对
B. 错