The figure shows the distribution of an ancient town and the direction of the streets in the ancient town, according to this answer 1 to 3 questions. The following about the figure of the river and th

The figure shows the distribution of an ancient town and the direction of the streets in the ancient town, according to this answer 1 to 3 questions. The following about the figure of the river and the ancient town is correct ( ) ① a ten section of the main reason for the formation of curved flow by the topography (plains) riverbed is easy to swing, and more curved flow, wrong; ② Ancient town siting of the river a bank - convex bank, the main relatively high terrain, the threat of flooding is less convenient to get water, correct; ③ riverbanks to get the bank of the convex bank, the role of siltation of sand is obvious in the summer for the flood season, the river c swim to bring more sediment, deposition is more significant, correct; ④ Riverbanks Ten banks for the scouring bank, by the river erosion is strong, easy to break the bank, correct; ⑤ ⑤ river bank a, 9, ten, get four places, the river bank ten slope is the steepest, wrong.

The choice: 9.

This is the first time that a river bank has been used as a bank for a long time.