Leonardo da Vinci(1452 – 1519) birds kept in cages in order to have the pleasure of setting themfree.[ ]

The boss in the factory often makes the workers _____ nine hours a day.

While shopping, people sometimes can’thelp______ into buying something they don’t really need.

It is a good habit of ______ to read something before going to bed.

Before a problem can be solved, it must be obvious ________ the problem itself is.[ ]