I've not seen him for a long time. He becomes stronger and more polite .
A:also
B:either
C:as well
D:as well as
①糖类 ②脂肪 ③蛋白质 ④水 ⑤无机盐
如图所示,A、B两个闭合线圈用同样的导线制成,匝数均为10匝,半径rA=2rB,
图示区域内有匀强磁场,且磁感应强度随时间均匀减小.
“m=-1”是“直线mx+2m-1y+1=0和直线3x+my+3=0垂直”的( )