World Wetlands Day is on________.
David finds ___ difficult to communicate with his parentsA.one B.it C.this
My cousin Mary was born ___ a singing voice.A.from B.in C.with
--How do you learn English?--I learn English ___ practicing conversations with friends.A.on B.by C.in
—You look very worried. ________ ?—My mother suddenly got ill yesterday.
I found _____ necessary to save energy and protect the environment.