grammar- sentence structure

1. I am strongly agree with you that one country should not attack another.
agree 係動詞，如果前面有 am ，一係就變 agreeing（現在進行式），一係就變 agreed（passive voice），不能不變。呢句睇唔出點夠要用現在進行式，所以：
I strongly agree...
2. To be a good salesperson, you must 〔刪去 be〕 talk to your customers, so your language skills will certainly improve.
唔只改一度喎
圖片參考：http://hk.yimg.com/i/icon/16/10.gif
。Must 同 will/shall/may/can/would/should/might/could 等 modal verbs 一樣，係面要跟一個動詞。talk 已經得啦，如果一定有 be ，就同第一句一樣，一係 talked，一係 talking。但此句係講「你一定要（經常）同客講野」，所以 simple present tense 已經得，故刪去 be。
3. Many ignorant people afraid that they will catch AIDS from a public toilet.
第一，afraid 係形容詞，唔係動詞，所以要講 be afraid。由於前面係 people（多過一個人），所以變成：
Many ignorant people are afraid that...
4. We must against the unfair treatment of employees in the workplace due to their race or gender.
against 一樣唔係動詞，而係 preposition。而 must 如上述必須有動詞跟住，所以其實漏左一個動詞。可以考慮：
We must act / work against the unfair treatment...

1. I am strongly agree with you that one country should not attack another.
I'm strongly agreeing with you that one country should not attack another.(agreeing)

2. To be good salesperson, you must be talk to your customers, so your language skills will certainly improve.
You must be talkative to your customers in order to be a good salesman so that your language skills will certainly be improved. (talkative , in order to and so that)

3. Many ignorant people afraid that they will catch AIDS from a public toilet.
Many ignorant person is afraid of their possiblity of diagnosing AIDS from a public toilet.( is and diagnosing)

4. We must against the unfair treatment of employees in the workplace due to their race or gender.
We must take action against the unfair treatment of employees in the workplace on the basis of gender and race.(on the basis of)