—How is your grandma?
—She is fine. She used to____ TV at home after supper. But now she is used to____out for a walk.
A:watch; going
B:watching; go
C:watch; go
下列说法正确的是 ( )
为了铸造金属工件,事先用密度为ρ1的实木材料制成木模,木模的质量为1.8kg.再用密度为ρ2的合金铸造30个这样的工件,这些合金的总质量为648kg,则木模与合金材料密度之比为( )