障碍物

shè zhì xiē zhàng ài wù

设置些障碍物

place obstructions

zhàng ài wù shí bié

障碍物识别

identify obstacles

tiān rán de zhàng ài wù

天然的障碍物

natural barrier

duǎn bō fā chū hòu yù dào zhàng ài wù jiù fǎn shè huí lai

短波发出后，遇到障碍物就反射回来。

When short waves are sent out and meet an obstacle, they are reflected.

jǐng fāng shè zhì le zhàng ài wù yǐ dǎng zhù rén qún

警方设置了障碍物以挡住人群。

The police put up barriers to keep the crowds back.