6. The machine can be very dangerous, especially when it ___________ in motion.
a. is
b. moves
c. goes
d. has

If you choose an answer because you like the sound of it, you should stick to it. English loves alliteration so there are many examples where the first letters in an expression are the same:

the coast is clear
it's a cheap and cheerful restaurant
he's a strong, silent type

There are also many poetic expressions in English. Which sounds better out of these:

time flies
time goes
time runs

The rhyme in the first one creates a better, more poetic effect and if you are unsure of the answer in this section of the Use of English paper, think about either alliteration or poetry.

Don't go changing all the answers at the end. Research shows that students are more likely to change a correct answer into a wrong answer than the other way around. Students will often pick an answer based on its "feel" or their instinct, based for example on the sounds we were talking about above. These "guesses" should be left as they are!

If you know the answer to a question, be happy about that, but also think about why the other three answers are not correct. This will build good vocabulary habits for you.