— There used to be a lot of fish in the lake many years ago.— Yes, but there are very _______ now because of the pollution.
I saw John ________ near the river on my way home.
—I'm very tired these days because of studying for physics. —Why not ________ music? It can make you ________.
—Hi, Tom! Can you tell me when ________ for London? —Yes, tomorrow afternoon.
Xiao Li said she would rather ________ join us.
Doctors tell people ________ their hands often and to stay home if they feel ill.