已知abc<0,a+b+c>0,那么a,b,c一定是[ ]
A.一正两负
B.全负
C.全正
D.两正一负
答案:D
—David has made great progress recently.
—_____, and _____. Keep up the good work, Tom.
A. So he has; so you have
B. So he has; so have you
C. So has he; so have you
开设哪些科目是教学计划的中心问题。