The same mistakes.～します/～しています
I want to tell you about the difference of between "～します" and "しています", but I've already known I find it difficult to explain it to you.
When I correct your Japanese, I often see the same mistakes.
The following are simple phrases and correct Japanese.
A-1: ご飯を食べます。
B:-1 野球をします。
C-1: 本を読みます。
D-1: 電話をします。
E-1: 映画を見ます。
...etc.
If I read only these sentences, I'll say "that's correct", but a lot of people learning Japanese use them the wrong way like this.
(on the phone)
Xさん：今、何してるの？
Yさん：ご飯を食べます。
If you want to express "I'm in the middle of eating something", that's not correct.
you must say "ご飯を食べています。".
If Xさん ask Yさん "お風呂に入った後は何するの？", the phrase "ご飯を食べます" is correct.
So you can't use A-1, B-1, C-1, D-1 and E-1 as "I'm in the middle of doing something".
They mean "I do something every day/once,twice...a week,a month" or "I'm going to do something/I'm doing something/I'll do something in the future".
Even if you use "今" with them, they don't mean "I'm in the middle of doing something".
It emphasize that you haven't started them yet.
When you want to express "I'm in the middle of doing something", you must say
A-2: ご飯を食べています。
B:-2 野球をしています。
C-2: 本を読んでいます。
D-2: 電話をしています。
E-2: 映画を観ています。
...etc.
