A.+→
B.→+
C.+→
D.→+
答案:D
I wonder if he _______ this weekend. If he ______, I’ll let you know.
A.will come; will come
B.will come; comes
C.comes; comes
D.comes; will come
泵将液体由低处送到高处的高度差叫做泵的()。
A.安装高度
B.扬程
C.吸上高度
D.升扬高度