题目

It's half past six! Please wake ___________. It's time __________ school. A . up him; for B . him up; for C . up him; to D . him up; to 答案：B7．已知f（x）=-x2+4ax-3a2，当1≤x≤2时，若f（x）≥0恒成立，求实数a的取值范围．