A:I1增大,I2不变,U增大
B:I1减小,I2增大,U减小
C:I1增大,I2减小,U增大
D:I1减小,I2不变,U减小
0.9×7+2.7=____
1.5×8×2=____
0×3.15+3.1=____
9.4-2.8×3=____
已知四棱柱ABCD﹣A1B1C1D1的底面ABCD是边长为2的菱形,AA1=23,BD⊥A1A,∠BAD=∠A1AC=60°,点M是棱AA1的中点.
(Ⅰ)求证:A1C∥平面BMD;
(Ⅱ)求点C1到平面BDD1B1的距离.
His order is that all of us ____(get) there before 5 o'clock.