TOEFL Listening: TPO-TOEFL阅读TPO - 8T1W3W4O2259Y735N$

According to paragraph 2, which of the following is true about bars in streams? A. They start forming in the stream channel and then expand over the banks B. They seldom form in rivers that are used for commercial navigation. C. They tend to grow longer each year. D. They often last no more than a year