A proton is an elementary particle of matter.质子是物质的基本粒子。an elementary English course基础英语课程Their course of study includes elementary hygiene and medical theory.他们的课程包括基础卫生学和医疗知识....
We tend to meet up for lunch once a week.我们往往每周共进一次午餐。We had lunch the other day at our favorite restaurant.前两天我们在最喜欢的餐馆吃了午饭。Grace laid out the knives and forks at the lunch-table.格雷丝把刀叉摆放在午餐桌上。...