已知圆锥的底面半径为4cm,高为3cm,则这个圆锥的侧面积为( )cm2.
20
A ______ is a person who is visiting a place when he or she is on holiday.[ ]
A. tourist
B. singer
C. Dentist
D. Waiter
下列单位中哪些是发光强度的单位()
A、摩尔
B、mol
C、坎德拉
D、cd
E、ccd