John can't go to the party on Thursday because he to go out on school nights.
A:allowed
B:is allowed
C:isn't allowed
计算:2×(2+12)-18-82.
考古发现是了解史前社会的重要证据,历史学家在北京人遗址中,发现了大量的灰烬、烧石、烧骨等,这反映出北京人( )