Where is my passport? I remember _______ it here.
You shouldn't have left it here. Remember _______ it with you all the time.
A.to put;to take
B.putting;taking
C.putting;to take
D.to put;taking
第1题:
—Where____you____lunch?
—Athome.Therewasnoschoollunch
A.did;have
B.are;having
C.will;have
D.do;have
第2题:
A)ashouldn't eat
B)mustn't have eaten
C)shouldn't have eaten
D)mustn't eat
第3题:
2、下列与关系代数的基本运算等价的元组关系演算表达式,表达不正确的是()。
A.RUS={t | R(t)∨S(t)}
B.R-S={t | R(t) ∧ S(t)}
C.σf(R) = { t | R(t) ∧ F}
D.πi1,i2,…,ik(R )={t(k)|(∃u)(R(u)∧t[1]=u[i1]∧...∧t[k]=u[ik])}
第4题:
第5题:
I’d rather you ________ make any comment on the issue for the time being.
A) don’t B) wouldn’t C) didn’t D) shouldn’t
选C
would rather that……"宁愿……",that从句中用过去时表示现在或将来要做的事。
第6题:
下列与关系代数的基本运算等价的元组关系演算表达式,表达不正确的是()。
A.RUS={t | R(t)∨S(t)}
B.R-S={t | R(t) ∧ S(t)}
C.σf(R) = { t | R(t) ∧ F}
D.πi1,i2,…,ik(R )={t(k)|(∃u)(R(u)∧t[1]=u[i1]∧...∧t[k]=u[ik])}