Can I say,

(a) He brought a basket of fruits for / to picnic with his friend.

(b) He brought a basket of fruits for a / the picnic with his friend.

(c)He brought a basket of fruits to his friends.
I think, it will be better:
He brought a basket of fruit for a picnic with friends.
If I say,

(a) We brought some fruits to the park this evening.
Students: Are you brave enough to let our tutors analyse your pronunciation?
1) What tense do you want to use? When this action was happened?
2) Look at this article to get the difference of using fruit and fruits. I hope ot would be very helpful.
Sorry, i can;t open that line. What's that article?

Some ‘fruit’ and ‘fruits’

I UNDERSTAND that “some fruit” and “some fruits” are both correct. Could you please explain? – Sheila Joseph

“Some” can be used with both uncountable nouns and plural countable nouns, as in “some bread” and “some chairs”.
The noun “fruit” can be either countable or uncountable, depending on context. It is usually uncountable when we speak of “fruit” in a non-specific way, for example in the sentence: “We must eat five servings of fruit and vegetables every day.”
Even when many different kinds are involved, we can still use “fruit” as an uncountable noun, for example when offering a guest a plate with slices of papaya, pineapple and melon, we say: “Have some fruit.”
When emphasising the different kinds of fruits, we usually use the countable noun, e.g. in the sentence: “I love Malaysian fruits, especially, guavas, mangosteens and papayas.”
When speaking of only one type of fruit, we can use “fruit” either as an uncountable or a countable noun. Below are some examples from a nursery website in the United Kingdom of how both “fruits” and “fruit” are used to refer to one type of fruit on one tree:
“Standard Lemon Tree. A vigorous plant to give a plentiful supply of juicy lemons. A lovely standard tree with fruits.”
“Your very own mango tree. What could be more exotic than that? Red and yellow fruits from June.”
“Avocado Tree. Dark-green, thick-skinned, pear-shaped fruit has buttery-textured flesh. Great for salads or home-grown Guacamole.”

(с) http://thestar.com.my/english/story.asp?file=/2007/3/15/lifefocus/17021531&sec=lifefocus

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