The roller coaster is moving _____ high speed. How exciting!
A:with
B:at
C:in
D:For
集合A={1,2}共有____ 子集.
幽赏未已,高谈转清。____,____。(李白《春夜宴诸从弟桃李园序》)
如图,已知∠ABC=180°﹣∠A,BD⊥CD于D,EF⊥CD于F.
(1)求证:AD∥BC;
(2)若∠1=36°,求∠2的度数.