Please help me see if I used right forms of tenses.

[wanglili]

I am wrting an essay for application. I don't know whether I have used the right form of tense in thses sentences. Could you tell me how should it be? Thank you!

1. I learnt that these students’ good performances in English tests largely came from extra tutoring outside of school. For families that cannot afford this, their children go to free tutoring organization to learn English with others much older or younger than them.

2.Their poor knowledge of English worried me because not even one of them complained to me about the script. According to my own experiencenevertheless, this lack of independent thinking is definitely an obstacle for them.......Another thing got me worried was .........

[billmcd]

I am wrting an essay for application. I don't know whether I have used the right form of tense in thses sentences. Could you tell me how should it be? Thank you!

1. I learnt that these students’ good performances in English tests largely came from extra tutoring outside of school. For families that cannot afford this, their children go to a free tutoring organization to learn English with others much older or younger than them.

2.Their poor knowledge of English worried me because not even one of them complained to me about the script. Nevertheless, according to my own experience nevertheless, this lack of independent thinking is definitely an obstacle for them.......Another thing that got me worried was .........

b.

[wanglili]

Thank you, b!