已知光的速度为300 000 000米/秒，太阳光到达地球的时间大约是500秒，试求出太阳与地球之间的距离大约是多少千米．（用科学记数法表示）

等差数列$\left\{a_n\right\}$前n项和为$S_n$，且$a_1=10,a_2=9$下列错误的是（     ）

小华轻松地戴上宽大的乳胶手套做家务，劳动后发现汗涔涔的手很难从手套中抽出，这是由于 ____导致手套与手之间的摩擦力 ____（变小/不变/变大）．

阅读短文回答问题

A: Could you tell me the way to the Sunshine School please?

B: Em, let me think about it.

A: I hope you can remind of it.

B: Yes, go down this street, then turn left at the third crossing（路口）, the Bus-stop is on your right, and you can take No. 10 bus to Sunshine School.

A: Wait...wait for a moment...I cannot catch it...Is it the first crossing?

B: No, the third crossing...

A: No. 10 Bus?

B: That's right. Are you clear?

A: Yes, clear. Thanks a lot.

B: You are welcome.