四边形ABCD中,对角线AC、BD相交于点O,要判别它是平行四边形,从四边形的角的关系看应满足( );从对角线看应满足( )
∠A=∠C,∠B=∠D ;OA=OC,OB=OD
用所给单词的适当形式填空。
1. Is it possible ______ (save)in any situation?
2. Aron still goes mountain ______ (climb),
3. The poor girl hurt ____ (she) in the accident.
4. They have much homework ____ (do).
5. The peanut was ____ (safe) removed by the doctor.
若塑件在两股熔料熔接处牢度不够,可采用()的方法解决。
A.塑件热处理
B.熔接处设冷料穴
C.增加充模速度
D.降低充模压力