题目内容：

There’s something rotten in Rio and the smell is coming from the huge stacks of rubbish piled up on sidewalks all over the city. Rio's street sweepers chose the carnival holiday to demand better salaries. Their wages start at roughly $400 a month.

There could hardly be a better time for them to prove their importance. The streets were left a mess after hundreds of carnival parades and now, rubbish pries up in both poor and uptown neighborhoods and in tourist areas like Ipanema or Copacabana beach.

The president of Rio's rubbish collecting company has even appealed to the population to store rubbish at home whenever possible. He says 30% of the city's sweepers have gone on strike. Some of those who have been working have been threatened by the strike movement so now the police have been deployed alongside rubbish collectors to keep them sage as they go about their business.

The strike has divided opinions in Rio. On social media, many support the sweepers' demands for better salaries. Others say they are opportunists and the situation is a big embarrassment to the city.

But Brazil's culture of littering the streets doesn't help. A video that went viral online shows that even authorities have a problem with that. Rio's mayor, Eduardo Paes, is seen throwing what seemed to be the rest of an apple on the sidewalk—and now promised to impose himself a fine for his wrongdoing. His government recently created a programme to keep Rio's residents from littering the streets.

1.Rio's street cleaners go on strike to ________.

A. prove their importance    B. ask for higher salaries

C. appeal to the public not to litter    D. threaten the government

2.The reason why the police are involved is that ________.

A. the police are called out to put down the strike

B. the police are called up to collect rubbish for the time being

C. the police are required to protect some cleaners

D. the police are sent to arrest people who litter around

3.The author's attitude to Brazil's culture of littering is ________.

A. critical    B. objective

C. supportive    D. optimistic

4.The purpose of writing the passage is to ________.

A. criticize street sweepers of Rio for misusing their rights

B. call attention to the embarrassing situation of Rio

C. describe the effect or the strike on people

D. inform people of the present situation of Rio