地球北纬45°圈上有A，B两地，分别在东经120°和西经150°处，若地球半径为R，则A，B两地的球面距离为（　　）

根据下列句子的句意、汉语提示或英语解释，写出空白处所缺单词的正确形式；每空一词。

1.He left home in a____ (匆忙) and forgot to turn off the light this morning.

2.Hearing the good news, we couldn't help____  (大笑).

3. In order to see the words on the blackboard more____ (清楚), she put on her glasses.

4.After a large____ (the meal you have in the morning), they set out for a hike in the mountain.

5.They had their school leavers’ party last ____ (the day between Friday and Sunday).

—Yes, I watched        at eight last Saturday.

读《散步》，这一切都使人想着一样东西——生命。

“这”是指代：（   ）