Phrases en français

20. J'aime les styles/la mode (plus) simple(s) parce que je peut porter (mes vetements) partout et ca ne prend pas beaucoup de temps pour m'habiller.

21. J'aime apprendre/etudier dans des espaces/endroits tranquilles

22. Chaque fois que je suis triste j’écoute habituellement de la musique. You can't both use "everytime" and "Usually", they conflict.

23. Je rêve d'avoir un jardin vide. This would mean "I dream of having an empty garden" if that's what you were going for.

24. En été, je vais acheté beaucoup de beaux vetements. Beau means Haokan or piaoliang for a masculine word. "Bon" means "good" which isn't something you'd use all that much with clothings unless you change "vetement" for another noun cause you could say it's a "bon produit" meaning a good product (of good quality).

25. Toutes les femmes veulent que leur mari (les) aide avec les taches ménagères. It's multiple husbands but each wife (most likely) has one husband hehe.

26. J'aime doux gâteau et je peut manger partout. You'd need to tell me what you want to say in English. That being said, "Doux" is usually "soft" though it is sometimes used to mean "sweet, but not too sweet" and or for sweet potatoes (patates douces)..Otherwise "sucré" is better.

27. L'homme ne peuvent pas éviter les faux. You'd need to tell me what you want to say in English.

28. J'aime le Français parce que c'est très intéressant

29. Je suis grosse et je veux perdre du poids. "perte de poids" means weight loss, a noun.

30. Je rêve d'avoir une vie heureuse. "vie" est un mot feminin.

31. Le cigarette est la cause de beaucoup de/plusieurs  maladies serieuses. Similar to English, you wouldn't use an adjective like "bad" unless you wanted to say "his/her condition is bad" or "he/she has a bad case of X". You can say Cancer is bad (i.e. a bad thing) but I definitely wouldn't say it's a bad illness, "serious" or a similar word would do better.

32. Nous devons sérieusement penser à la protection de l’environnement. Very good, just slight confusion between "serious" (use with  a noun) and "seriously" (use with a verb like "penser")

33. Quand je suis vieux je veux habiter avec les enfants. Quand je serai plus vieille (vieux is for men), je veux avoir des enfants. (When I will be/I'm older, I want to have kids) . To live with kids is a weird turn of phrase cause it'd mean you have like kid roomates or something ;).

34. Je pense toujours je dois fait vrai. You'd need to tell me what you want to say in English

35. Années ancien, La vie est simple et l'homme sont sympathique. I'm not sure what you want to say, but if it's something like "In the past, life was simpler and people were friendlier" it'd be "Dans le passé, la vie était plus simple et les gens plus sympatiques. We don't use "L'homme" as it is used more for us as a species like "mankind" not just as a synonym for people.

36. Quand il fait beau, je fait souvent du sport avec mes amis. Good words, wrong order ;)

37. J'aime les bols blancs. Same as above.

38. Certain pays pauvres n'ont pas assez de nourriture pour tout le monde. This would mean that some poor countries don't have enough food to feed everyone if my guess about your meaning is accurate.

39. Le climat est de  plus en plus chaud en raison du changement climatique. Great.

40. Je n'achete pas de vetements chers. ne, de, etc...become n', d' and so on with a vowel or (mute) H.

42. Les nuits d’été il y a beaucoup .d'étoiles brillantes/lumineuses. "Clair" is more "bright" as in "Il fait clair dehors" (It's bright outside)

Alright this is already alot of info and notes, but let me add a few mini-lessons:

- Most of the time, we put adjectives after the noun in French (e.g. J'aime les bols blancs) though there are some exceptions (de beaux vetements)

- Keep track of words like "de" or "que" after common verbs or expression. A chaque fois que...Je vois beaucoup de....Je reve de/d'.... This isn't always true, but a tip would be that if there's a "that" or "of" or something like that in English, most likely there is one in French too.

- "Beaucoup de" (alot of...) stays like that even though you'd be tempted to use "des" (e.g. J'ai beaucoup de vetements dans ma chambre/I have many clothes in my room).

Good luck with the learning ;)