Mark the letter A, B, C, or D to indicate the correct answer.

This is the first time I ________ on the Ha Noi Metro.
1. have travelled
2. will travel
3. travel
4. travelled
The ________ serious the air pollution in the city is becoming, the ________ its negative impact is on people's life there.
1. less … more
2. more … bigger
3. fewer ... fewer
4. more … less
________ people now tend to move to big cities to look for better job opportunities.
1. More and less
2. Less and less
3. More and more
4. Fewer and fewer
My grandparents don't want to live in the city ________ they don't like the crowded streets and the traffic jams.
1. although
2. because
3. moreover
4. if
The increasing number of private cars causes traffic jams; ________, it is also the main reason for air pollution in big cities.
1. as a result
2. on the other hand
3. so that
4. moreover
Local authorities have improved the frequency of public transport ________ more people will find it convenient to use.
1. so that
2. not only
3. such that
4. neither