--What are you doing? ---- I am _____ a letter.A.sending B. writing C.Both A and B
( ) You should ___________ your little brother when your mother is out.
( ) Sometimes walking is __________ than driving during the busy traffic time.
( ) My sister was born _____________ a Friday morning.
( ) Mary is a student of___________.
( ) What __________ useful book! And __________book is very interesting.