What does the word they in line 2 refer to?

Read the following passage and mark the teller A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

    Mercury is the smallest member of the sun's family which is only 3,100 miles across. It is also the sun's swiftest planet. Its yearly journey round the sun is only 85 days.

   Mercury always keeps one side towards the sun. On this side it is always day, on the other side it is always night. We only see the lighted side.

   Mercury appears to us like a yellowish orange star. The nearest planet to the sun, it is always seen near the sun, either just before sunrise or soon after sunset. People sometimes call Mercury the morning star or evening star. Mercury is half the size of the earth. Because it is much lighter, it has much less gravity. If you can visit Mercury in a spaceship, you will find it a strange world. Its low gravity makes you feel very light. If your weight on earth is 100 pounds, your weight on Mercury is only 27 pounds. Looking at the sun from Mercury, you can see that it’s much more brilliant than it is seen from the earth. And the yellow centre of the sun appears three times bigger from Mercury. On the lighted side, Mercury’s temperature is about 300 degrees centigrade. But the dark side is extremely cold, 150 degrees below zero so Mercury is probably the coldest as well as the hottest of the planets.

 The word swiftest in paragraph 1 is closest in meaning to ______.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the word that best fits each of the numbered blanks.

      English is my mother (31) ______. Besides, I can speak French and Spanish. I studied these two languages when I was at high school. Now I am still learning Spanish at University. As tor me, mastering a foreign language is not easy. After studying a language, I find that practice is very necessary and useful. Travelling to the country where the target language is spoken is very helpful, (32) ______ if you cannot speak the language well enough, you will certainly have troubles. I also frequently go to the movie, watch television, listen to the radio in the language (33)______ I           am trying to learn. Reading is another good way to learn. Books are good, but I personally think newspapers and magazines are better. However, getting (34)         ______ knowledge of the language is one of the most (35) ______ things. That’s the reason why grammar and vocabulary should be mastered first.