Happy New Year ___________ you![ ]
A. at
B. to
C. on
答案：B
圆柱的体积比和它等底等高的圆锥体积多______．
已知x2+4y2+kz2=36，（其中k＞0）且t=x+y+z的最大值是7，则 k=______．
