①与足量的NaOH溶液共热后，再通入CO₂   

②与足量的NaOH溶液共热后，通入足量的稀盐酸

③与稀H₂SO₄共热后，加入足量的NaHCO₃饱和溶液

④与稀H₂SO₄共热后，加入足量的NaOH溶液

A．只有①

B．①②

C．①③

D．①③④

In country after country, talk of nonsmoker’s right is in the air. While a majority of countries have taken little (51) no action yet, some 30 nations have introduced legislated steps to control smoking. Many laws have been introduced in other countries to (52) clear the air for nonsmokers, or to cut cigarette consumption.

Smoking is harmful (53) the health of people. World governments should conduct serious campaigns against it. (54) on cigarette advertisements, plus health warnings on packages and ban on public smoking in certain places, (55) as theaters, cinemas and restaurants, are the most popular tools used by nations in (56) of nonsmokers or in controlling smoking. But world attention is also focusing on another step (57) will make the smoker increasingly self-conscious and uncomfortable about his habit. Great efforts should be made to (58) young people especially of the dreadful consequences of taking up the habit. And cigarette price should be raised.

In the long run, (59) is no doubt that everybody would be much better-off if smoking were banned altogether but many people are not (60) for such drastic action.

57().

A.so 

B.as 

C.which 

D.such