某种蛋白酶是由129个氨基酸脱水缩合形成的蛋白质，下列叙述正确的是（ ）
A：该蛋白酶分子结构中至少含有129个氨基和129个羧基
B：利用透析法纯化该蛋白酶时，应以蒸馏水作为透析液
C：洗衣粉中的蛋白酶对皮肤有损伤，因为皮肤的成分主要是蛋白质
D：用含该蛋白酶的洗衣粉去除油渍，效果比其他类型加酶洗衣粉好
选择正确的一项。
( ) You ______ six.
已知等腰三角形的内角是40°，则另外两个内角的度数分别是（ ）
Many students get a driver's permit at 15. In California, they are then allowed to drive for 50 hours under supervision. “Under supervision” means that a friend or relative who already has a license has to ride with them. But what happens when teenagers (persons between 13 and 19 years old) start driving on their own? Many are careful drivers and never have a problem. But many others are not, and they create(造成) problems on the road. Fifteen-year-olds are too young to drive, and sixteen-year-olds are too immature(不成熟的) to start driving alone. In the United States, more teenagers are drilled in driving accidents than in any other way. While fewer than 7% of all drivers are teenagers, teenagers are involved(占；包括) in 14% of the terrible car accidents in the country. Sixteen-year-olds are involved in over 43 crashes in every million kilometers they drive. But seventeen-year-olds cause only about 30 accidents in a million kilometers of driving. One year makes a difference. So the age limit(限制) should be increased.
