Question

I don’t know _________.

A．what to do it

B．how to do it

C．what to do

D．to do what

Answer 1

C

考查疑问词+不定式。what to do中，what作do的宾语，A项it多余，排除A；D项的疑问词应该放前面，排除D。 how to do中缺少宾语，排除B。故选C。