o teaching, as we know, contributes to his popularity with his students.

________ in looking after three children athome, she no longer has time to enjoy various activities in theclub

They ________ all the details of the plan time and again to make sure that the project would go smoothly.[ ]

The speaker _____ pronunciation is the bestwill get the first place

It is wise of you towell trained workers for untrained ones in your workshop. A．substitute B．changeC．exchange D．employ