1.我的名字是 Amanda. 

Wǒ de míngzì shì Amanda.
My name is Amanda.
我叫/個名係 Amanda。

2.我研究了很多.
Wǒ yánjiūle hěnduō.
I study a lot.
我學左好多。p.s.I ’m not sure whether you mean learn or investigate something.In Chinese,研究 usually means investigate or a research study.If you want to say learn to drive,learn to cook,learn to speak etc.,you should use 學 instead of 研究.

3.为什么没人教我广东话？
Wèishéme méi rén jiào wǒ guǎngdōng huà?
Why nobody teaches me Cantonese?
點解無人教我廣東話？

4.我用QQ
Wǒ yòng QQ
I use QQ
Ok:)

5??

HTH:]