1.by accident偶然地，意外地
e.g.:The scientist died by accident suddenly.2.smell和taste的用法
(1) n. smell味道(闻到的);taste味道，品味(尝起来的)
(2）vt. smell闻…....;taste品尝.…....
(3）连系动词:smell 闻起来;taste尝起来
e.g.:He smelt the fish.He felt the smell was bad,so hedidn't taste it.
3.辨析happen和take place(1)happen发生(指突然发生)
e.g.:The earthquake happened suddenly.(2) take place发生(指按计划发生)e.g.:Big change took place in our town.4.in the 19th century在19世纪
in the +序数词+century表示“....…世纪”【拓展】in the 1980s在20世纪80年代5.without doubt毫无疑问
e.g.:He knows the truth without doubt.