对矩阵a进行初等变换冰化为行最简形记为B
A. 对
B. 错
By the end of this year ,I ____enough money for a holiday
A. will save
B. will be saving
C. will have saved
D. have saved
I have been studying here for four years by next summer ____.
A. shall graduate
B. shall be graduated
C. shall be graduating
D. shall have graduated
I hope her health _______greatly by the time we come back next year.
A. improves
B. improved
C. will be improved
D. will have improve
微信支付 
支付宝支付