This is a great drawing by one of the 19th century's finest draughtsmen.这幅恢宏画作出自一位19世纪最杰出的画家之手。Draughtsmen make drawing on a drawing board, a pencil a T - square , set square and scale.绘图员用铅笔 、 丁字尺、三角板和比例尺在绘图板上绘图....
这些试验的有效性已显得令人怀疑.The tests have been shown to be of dubious validity.他们正在检测这种草药作为杀菌剂的有效性.They're doing tests to evaluate the effectiveness of this herb as an antiseptic.蛋白质还可以作为检测实验治疗有效性的标识物.They can serve as markers...