A,t＜－1.5 B,t＞－1.5 C,t＜－3 D,t＞－3

A,t＜－1.5 B,t＞－1.5 C,t＜－3 D,t＞－3 （ ）－Must I do my homework at once?A.needn't B.mustn't C.can't（ ）－Must I do my homework at once?A.needn't B.mustn't C.can't D.may not A computer____think for itself .A.mustn't B.needn't C.can't D.isn't My parents_____home.A.weren't B.didn't C.weren't be D.didn't be Mary and Linda___here now.A.aren't B.don't C.isn't D.doesn't I__think they__clever.A.don’t,are B./,aren’t C.Don’t,aren’t He______a teacher?A,don't B,doesn't C,isn't D,aren't 已知a=(1-t,2t-1,0),b=(2,t,t）,则｜b－a｜的最小值是（） （A）根号5 （B）根号6 （C)根号2 （D）根号 求一元四次方程解法R=r(1+a*t+b*t*t+c*t*t*t*(t-100)) 用R r a b c表示t,既：t等于什么?R r a b c均为常数 T=[(b/a)+(d/c)] Don't go that way,sam.----no,i_____ A.mustn't B.don't C.won't D.can't 已知向量a＝（1-t,1-t,t）,向量b=（2,t,t）,则|向量b－向量a|的最小值为多少? 物体加速度随时间变化a(t)=At-Bt^2,A=1.5m/s^3,B=0.120m/s^4,v(t)=∫a(t)dt+C中∫a(t)dt该怎么计算? They ( )have a bike.A.doesn't B.don't C.aren't D.not Jeff____have a soccer ball .A.don't B.is't C.does't We _call it a cat A:doesn't B:aren't C:don' t we_call it a hen.A:doesn't B:don't C:isn't They _____ having a picnic.A.don't B.aren't C.can't选哪个?