1) Who is {he, she} 他是谁 : who is he ? 她是谁 : who is she ? (pronunciation is exactly the same) 2) Please come in ( 请进 )

他是谁？who is it? 请进 please come in

I am learning English now. "Ta shi shui?"他是谁 who is he? "Qing jin!" 请进 come in.