Nobody knows ______ yesterday.
A:how the accident happens
B:how does the accident happen
C:how the accident happened
D:how did the accident happen
比较大小:52°52′____ 52.52°.(填“>”、“<”或“=”)
下面是某同学在实验课上“制作洋葱内表皮细胞临时装片”时的某些片段,请你仔细回忆自己做该实验的情景,并按要求回答下列问题: