国家创新系统包括()。
A.政府部门
B.企业
C.教育培训机构
D.科研机构
参考答案:A, B, D
Computers and mobile phones, though they are indeed making our life______and more ______, have reduced the need for face-to-face communications.
A.easily ; efficient
B.easier; efficient
C.easy ; efficiently
D.easily ; efficiently
泵叶轮经车削后,泵流量()。
A.不变
B.增大
C.减小
D.加倍