一般不引起乳牙滞留的是
A.乳牙到替换期后长期不脱落称乳牙滞留
B.乳牙滞留经常出现在乳切牙和乳尖牙
C.恒牙先天缺失使乳牙根吸收缓慢导致滞留
D.乳牙根尖病变致使骨组织吸收恒牙早萌乳牙滞留
E.乳牙外伤导致牙齿固连滞留
第1题
You ______ him out though you were very busy.
A.could have helped
B.must help
C.should have helped
D.ought to help
第2题
______ we not helped him, he would have been hurt by the truck.
A.Had
B.Have
C.If
D.Until were
第3题
A.Without you helped us
B.But for you helped us
C.But you helped us
D.If you had not helped us
第4题
If it__________ possible, I would have helped him, but I was too busy.
A.is
B.was
C.were
D.had been
第5题
A.Without you helped us
B.But for you helped us
C.If you had not helped us
D.But you helped us
第7题
A、 about
B、 in
C、 out
D、 up
第8题
A、 why
B、 because
C、 for
D、 as
第9题
A、 studying
B、 to study
C、 to have studied
D、 having studied
第10题
A、 to leave ... Alone
B、 leave ... Lonely
C、 leave ... Alone
D、 to leave ... Lonely
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