I _________ school on foot, but now I _________ so by bike.
A:used to go; used to doing
B:used; am used to do
C:used to going; am used to do
D:used to go; am used to doing
在制作口腔上皮细胞临时装片时,将标本放于( )中
①反映了社会生活的变化
②佐证了语言的相对稳定性
③与社会发展完全同步
④是对社会生活的能动反映