I should not have laughed if I________ you were serious.
In 1492 Columbus and his crew arrived ______ was so-called the New World by the westerners.
—It is _______he often fails in exams_______ makes his parents worried about him. —So, he has to work whole-heartedly.
In some countries, ______ is called “equality” does not really mean equal rights for all people.
The police were seeking more information to find out ______ the rich merchant.
_____ puzzles me most is that I don’t know ______ the difference between the two lies.