16. The river, ______the bank are covered with trees, is very long.
Your hand is dirty. It needs ____________.
After the new equipment was introduced, they produced ______machines this year as the year before.
Can you make sure_______ the gold ring?
There’s only ten minutes to go. We can’t wait any more---- ______, we should start at once.
In the past ten years, the ________mountain climber _________ a lot from his own adventurous _______