Combine two sentences into a new one using the given words in brackets.

Has anybody shown you what to do? (Have)

Air (23)…………..is caused of ill-health in human beings. In a lot of countries, there are laws limiting the amount of smoke which factories can (24)…………..although there is not enough information on the effects of smoke on the atmosphere. Doctors have proved that air pollution causes lung diseases. The gases from the exhausts of cars also (25)………….. air pollution in most cities. The lead in petrol produces a poisonous gas, which is often (26)…………..in busy streets circled by buildings. Children who live in areas where there is  (27)…………..lead in the atmosphere cannot think as quickly as other children, and are clumsy when they use their hands.

The bamboo used to make conical hats must be split into very thin strings and then put into water…………...they can avoid tearing and any breakage.

Mark the letter to indicate the word whose underlined part differs from the others in the position of primary stress.

I’m usually right about the weather, am not I?