观察下列式子,正确的是[ ]
A.a+3>3
B.﹣2x(x﹣3y)=﹣2x+6y
C.16y2﹣7y2=9y2
D.4÷(2+1)=4÷2+4÷1
When first ______to Britain, tea was not so popular like today
.
A.introducing
B.introduced
C.being introduced.
D.introduce
2安培的设备保险丝断了,可以使用3安培的代替。