Dialogues　

1. 最近我牙疼。Zuìjìn wǒ yá téng.
I’m suffering from toothache these days.
最近我牙疼. It means I have a toothache recently.
最近 zuìjìn, both in the fourth tone ,which means recently.
我 wǒ, the third tone, which means I.
牙 yá, tooth, the second tone.
疼 téng, ache, also the second tone.

2. 应该吃什么药呢？Yīnggāi chī shénme yào ne?
What medicine should I take?
It would be ok if you get some medicine from a pharmacy.Then you can ask the workers there应该吃什么药呢?
应该 yīnggāi, both in the first tone, which means should.
吃 chī, to eat or take.
什么 shénme, what.
药 yào, medicine.
呢 ne, here comes at the end of the sentence, indicating this is a question.

3. 这种药效果不错。Zhè zhǒng yào xiàoguǒ bú cuò.
Generally speaking the workers in the pharmacy may give explanations like “This drug works well”.
The Chinese for that is 这种药效果不错.
这种 zhè zhǒng, this kind of.
药 yào, medicine.
效果 xiàoguǒ, effect.
不错 bú cuò, not bad.