——I often have hamburgers for lunch.
——You'd better not. It's bad for you _________ too much junk food.
A：eat
B：to eat
C：eating
D：ate
世界文化遗产长城总长约为6 700 000m，若将6 700 000用科学记数法表示为6.7×10n（n是正整数），则n的值为 ( )
人体的血液属于（ ）
