Although there are some affordable eco-friendly cars, cars are, as a rule very harmful to the environment. What does ‘as a rule’ mean?

For bus travel to be popular among normal people, have a low price is of the essence. What does ‘STH is of the essence’ mean?

I think that the local government should rise to the challenge and try to reduce the number of cars on the roads. What does ‘rise to the challenge’ mean?

In a nutshell, the government should do more to promote the use of public transport. / All in all, the government should do more to promote the use of public transport. What do ‘in a nutshell’ and ‘all in all’ mean?

People will always want the convenience of private cars, so the bottom line is making those cars less harmful for the environment. What does ‘the bottom line is’ mean?

Since the expansion of the metro and bus systems, the congestion problem has improved by leaps and bounds. What does ‘STH has improved by leaps and bounds’?

Some people are strongly against this idea, and others strong support it, but I’m on the fence because I can see both the good points and bad points. What does 'on the fence' mean?

The air pollution caused by the large amount of traffic brings us health problems like coughing and sneezing, but these might actually be the tip of the iceberg: there might be more serious long-term health problems like lung cancer. What does ‘the tip of the iceberg’ mean?

The impressive underground rail system in Singapore has put it on the map. What does ‘put a place on the map’ mean?

The key to solving air pollution is to make public transport better and cheaper. What does ‘the key to doing STH’ mean?

The number of cars on the roads in the city has rocketed in recent years. / The number of cars on the roads in the city has shot up in recent years. What does ‘STH has rocketed/STH has shot up mean?

There are many advantages and disadvantages of cars, but on balance I think they are more beneficial than harmful. What does ‘on balance’ mean?

There are many dangers of motorbikes, and top of the list is the risk of dying in a collision What does ‘(at the)top of the list’ mean?

There are so many cars on the road that it has caused a lot of air pollution. Because there is so much air pollution, people are unwilling to walk or cycle, so they travel by car, which leads to more pollution. It’s a vicious circle. What is a ‘vicious circle’?

Choose an appropriate formal idiom to complete the following sentence:

The ________________ improving your English is reading as many books as possible.

Choose an appropriate formal idiom to complete the following sentence:

Having fried chicken in our canteen is just _______________. More serious dieting problems will be revealed soon.

Choose an appropriate formal idiom to complete the following sentence:

_________________, it seems that learning basic subjects, such as English and Maths, has brought more positives than negatives.

It goes without saying that regular physical exercise is ________________ in maintaining a healthy body.

In response to the call for a green campus, our school should ____________________ and try to go paperless.