2. 如果先行词被形容词最高级以及first, last, any, only, few, much, no, some, very 等词修饰，关系代 词常用that, 不用which, who或whom
3. 如果关系代词紧跟在介词后面，不能用who或 that， 只能用which 或whom。
4. 在非限从句中，不能用that, 做宾语的代词也不可 省略。
Go for a short walk, usu. After you have been sitting down for a long time.
Office workers need to stretches their legs from time to time because their working style is too sedentary.
The internet affords convenience to many. (给予，供给）
10Leabharlann in session: not on vocation 不在休假期； assembled for business 开庭，开会
Are American universities in session during August? The court is now in session.
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Yellowstone National Park is the United States' — and the world's — first national park, established by the US Congress on March 1, 1872. Covering over 2.2 million acres/899,000 hectares, the park is larger than the states ofRhode IslandandDelawarecombined. There are nine visitors centers and museums, nine lodging facilities hosting a total of more than 2,000 rooms, more than 2,000 camping sites, about 50 picnic areas and a marina.
