16. There was so much noise produced by the machine outside that the professor had to ______ his voice so that it would not ________.
This work, when we find it and do it----_________only as a hobby at first---is a key to our true happiness.
.The vocabulary and grammatical differences between British and American English are so few and unimportant as hardly______.
Nowadays, many young people have no idea how to get to_____they want to go.
The declaration____saving the rivers and giving people their traditional rights over them.
.Young________, he already knows what career he wants to follow.