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1. A student who may have a vocabulary of thousands of words has studied English for a few years.

2. Between formal and colloquial English there is unmarked English, which is neither so literary and serious as formal English, nor so casual and free as colloquial English.
3. He bought a jeep although his friend advised him against it.
4. Though good writing requires general and abstract words as well as specific and concrete ones, it is the latter that make writing vivid, real and clear.
5. It was raining so hard that they could not work in the fields.
6. The politician is concerned with successful elections, whereas the statesman is interested in the future of his people.
7. Although the results of the experiment were successful, the school refused to give any help.
8. He chose to study computer science because of the good employment prospects.

9. If Mary hadn't walked very slowly, she would have caught the train.
10. In the event of his not coming, the meeting will be put off till next week.