L.f.d.
[医] 最低致死量(毒素)
🗣️ 情景例句
His studies haven't been inproving lately.
他的学业最近没什么进步。
To skydive
漫游太空
Instruments have been devised and can be so placed that all three elements can be recorded in different graphs.
已经设计出了一些仪器，它按照一定的安放方式就可测绘出这三种运动的曲线图。