37（）

单项选择题The purpose of the scientists in studying tree rings is to （）。

A. examine the chemical elements in the Ice Age
B. look into the pattern of solar wind activity
C. analyze the pattern of solar wind activity
D. find out the origin of carbon-14 on earth

单项选择题Of the risky activities, bungee jumping （）.

A. offers an immediate excitement
B. is a fashion
C. makes one relaxed
D. makes one brave