18 Put the verbs in brackets into the correct form and read the joke. (to buy) a parrot which could already talk. However,
the man soon ... (to discover) that the parrot mostly
(to be) funny, but then
bad words. At first he ... (to think) it
important guests, the bird's bad words ... (to embarrass) him
it ... (to become) tiresome, and finally, when the man
very much. As soon as the guests ... (to leave), the man angrily
(to shout) at the parrot, «That language must stop!» But the
bird ... (to continue) saying bad words. Now the man
really angry. He ... (to grab) the parrot and
the refrigerator. But it ... (to have) no effect. From inside the
refrigerator, the parrot still... (to say) nasty words. Then the man
(to open) the door of the freezer,
and ... (to close) the door. This time there ... (to be) silence. After
(to be)
(to put) it into
(to throw) the bird into it,
two minutes, the man... (to open) the door and ... (to remove) the
very cold parrot. Slowly the shivering parrot
(to walk) up the
man's arm, ...
(to sit) on his shoulder and ... (to speak) into his
ear, sounding very frightened, «I'll be good, I promise... Thos
chickens in there... . What ... they ... (to say)?»
​

The correct form of the verbs in the text should be as follows:

"18 Put the verbs in brackets into the correct form and read the joke. (to buy) a parrot which could already talk. However, the man soon discovered (to discover) that the parrot mostly was being (to be) funny, but then started saying bad words. At first he thought (to think) it was imitating important guests, but the bird's bad words were embarrassing (to embarrass) him and it became (to become) tiresome, and finally, when the man had had enough, he shouted (to shout) at the parrot angrily, 'That language must stop!' But the bird continued (to continue) saying bad words. Now the man was really angry. He grabbed (to grab) the parrot and put it (to put) into the refrigerator. But it had (to have) no effect. From inside the refrigerator, the parrot still said (to say) nasty words. Then the man opened (to open) the door of the freezer, threw (to throw) the bird into it, closed (to close) the door. This time there was (to be) silence. After two minutes, the man opened (to open) the door and removed (to remove) the very cold parrot. Slowly the shivering parrot walked (to walk) up the man's arm, sat (to sit) on his shoulder and spoke (to speak) into his ear, sounding very frightened, 'I'll be good, I promise... Those chickens in there... What did they say?'"