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

Sometimes knowing what isn't right is just as important as knowing what is. Learns the art of elimination. If you can get rid of one or two options, your chances of guessing right increase significantly.

Read a variety of English materials regularly – books, articles, blogs, etc. The more you read, the better your instinct for what 'sounds right'. It's like tuning an instrument; the more you do it, the better you'll get at playing the language.

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.

Don't spend too much time on one question. If you're stuck, it's better to move on and come back later with fresh eyes.