adv.周期性地;定期地
New strains of viruses appear periodically. 新菌系的細(xì)菌周期性地產(chǎn)生。
The state of knowledge in this field has been surveyed periodically in review papers. 在一些評論文中對這一領(lǐng)域的動態(tài)周期性地進(jìn)行了評述。
Periodically, someone comes by with a truck to fill them. 有些人定期地用卡車運(yùn)輸食品,裝進(jìn)機(jī)器。
不定期地