R and d program
[经] 研究与发展, 开发规划
🧩 词语组成解析
and
[ənd, ən,ænd]
conj. 和，与;而且;于是，然后;因此;
🗣️ 情景例句
What's the problem, Richard?
有什么问题吗 Richard
I'm sorry to have kept you waiting.
很抱歉，让你久等了。[分词作状语]
The dentist is very busy at the moment.
牙科医生这会儿很忙。