抛物线y=x2-2mx+m2+m+1的顶点在
A．直线y=x上
B．直线y=x+1上
C．直线y=-x上
D．直线y=x-1上
答案：B
一菜店购来梨344千克，比西瓜的4.5倍少16千克，购来西瓜多少千克？
When speaking in public, it is important to _____ your message _____ and keep the attention of your audience. [ ]
A. get…through
B. get…into
C. get…over
D. get…across
