6300与500的和是多少?差是多少?
6300+500=6800;6300-500= 4800
His mother __________ a special meal for his birthday.[ ]
A. made
B. be
C. did
D. make
我国的《公路沥青路面再生技术规范》建议水泥等活性填料一般不超过()
A.1%
B.1.5%
C.2%
D.2.5%