往复

wǎng fù shì yā suō jī

往复式压缩机

reciprocating compressor

xún huán wǎng fù

循环往复

move in cycle

wǎng fù bèng

往复泵

reciprocating pump

shū xìn wǎng fù

书信往复

exchange letters

bīn zhǔ wǎng fù

宾主往复

contact between the host and the guest