题干
Mike: Let's have a big meal.
Lily&Emma: Wow, we like the pizza.
John: I like pizza, too.
Mike: Do you like hot dogs, Sam?
Sam: Yes, I do. What about you, Mike?
Mike: Me too.
选择正确的答案填在括号里。
Mike: Let's have a big meal.
Lily&Emma: Wow, we like the pizza.
John: I like pizza, too.
Mike: Do you like hot dogs, Sam?
Sam: Yes, I do. What about you, Mike?
Mike: Me too.
选择正确的答案填在括号里。
简谐振动，其振动图象如图1所示，根据图象可知，在t1和t2时刻，物体运动的（ ）