The beautiful song ________ me of those happy old days we had spent together.
The foreign guests, ____ were government officials, were warmly welcomed at the airport.
He is writing a letter______ a pen that I have never seen before.
________ the boy didn't take medicine made his mother angry.
I don’t know ________ is in charge of English department.
---Susan is so excited!---Oh, yes! She is busy preparing for her trip to Africa that she _____ for years.