单项选择题 The primary impulse of each human being is to（）himself, but the secondary impulse is to venture out of the self, to correct its provincialism and heal its loneliness.

单项选择题 Current estimates put thirteen percent of global flora at risk of extinction, but this number does not include （） plants from tropical regions, where the majority of the world's plants grow.

单项选择题 The teacher has （） catering to some students, but to retain his tenure, which effects only after a teacher has unanimously gratified his students, he offers his complaints （）.