Clauses and phrases of purpose
A purpose clause introduced by so that can sometimes be replaced by prevent/avoid + gerund or allow/enable/let/make etc. + infinitive.
The two sentences:
He rumpled the bedclothes. He wanted to make me think he had slept in the bed.
could be combined:
He rumpled the bedclothes so that I should/would think he had slept etc. or to make me think he had slept etc.
An in case clause is useful when we mention the possible future action we are taking precautions against:
Don’t let him play with scissors. He may cut himself.
could be expressed:
Don’t let him play with scissors in case he cuts himself.
Sometimes an in case clause can be replaced by a negative purpose clause.
1 He killed the men who helped him to bury the treasure. He wanted nobody but himself to know where it was.
2 Put the cork back. Someone may knock the bottle over.
3 The airfield authorities have put arc lights over the damaged runway.
They want repair work to continue day and night.
4 The girl packed the vase in polyester foam. She didn’t want it to get broken in the post.
5 He wore a false beard. He didn’t want anyone to recognize him.
6 She built a high wall round her garden. She didn’t want her fruit to be stolen.
7 They talked in whispers. They didn’t want me to overhear them.
8 You ought to take some serum with you. You may get bitten by a snake.
9 Aeroplanes carry parachutes. The crew can escape in case of fire.
101 am insuring my life. I want my children to have something to live on if I am killed.
11 Please shut the gate. I don’t want the cows to get out of the field.
12 He telephoned from a public call-box. He didn’t want the call to be traced to his own address.
13 I am putting nets over my strawberry plants. I don’t want the birds to eat all the strawberries.
14 We keep a spade in the house. There may be a heavy fall of snow in the night.
15 We put bars on the lower windows. We didn’t want anyone to climb in.
16 You should carry a jack in your car. You may have a puncture.
17 We built the roof with a steep slope. We wanted the snow to slide off easily.
18 The notices are written in several languages. The government wants everyone to understand them.
19 I put my address on my dog’s collar. I want anyone who finds him to know where he comes from.
20 She tied a bell round her cat’s neck. She wanted the birds to know when he was approaching.
21 Bring your gun with you. We may be attacked.
22 I have put wire over my chimney-pots. I don’t want birds to build nests in them.
23 Write your name in the book. He may forget who lent it to him.
24 He chained up the lioness at night. He didn’t want her to frighten anyone.
25 Don’t put on any more coal. The chimney may catch fire.
26 The burglar cut the telephone wires. He didn’t want me to call the police.
27 Take a torch with you. It may be dark before you get back.
28 The manufacturers have made the taps of their new gas cooker very stiff. They don’t want young children to be able to turn them on.
29 Don’t let the baby play with my glasses. He may break them.
30 The debate on education has been postponed. The government want to discuss the latest crisis.
31 If someone knocks at the door at night don’t open it. It may be the escaped convict.
32 The policeman stopped the traffic every few minutes. He wanted the pedestrians to be able to cross the road.
33 He had a telephone installed in his car. He wanted his secretary to be able to contact him whenever necessary.
34 Never let children play with matches. They may set themselves on fire.
35 As he went through the forest Bill marked the trees. He wanted the rest of the party to know which way he had gone.
36 Turn down the oven. We don’t want the meat to burn while we are out.