It’s a rule for all the students to ____ their places ahead of 5 minutes waiting for the class to be started.

A．take up

B．pick up

C．keep up

D．give up

口腔医疗保健中由接触传染的主要疾病是

A．水痘

B．麻疹

C．流行性腮腺炎

D．念珠菌病

E．病毒性肝炎