Using particles excessively?

Question

I've been using Duolingo for the better half of my Japanese learning experience but recently I purchase the McGraw's Complete Japanese Grammar for more comprehensive learning.

I'm on chapter 7, which is about particles (を、が、は、に…). And so far I'm doing good with the particles themselves, but with later questions where ask you to translate entire sentences with more particle usage than the given answers. Which online translates think it's all right.

Such as:

1. I only have a bicycle.
   • Given answer: 自転車しかありません。
   • My answer: 自転車しかがありません。
2. I only ate ramen.
   • Given answer: ラーメンしか食べませんでした。
   • My answer: ラーメンにしか食べいませんでした。
3. My little sister read nothing but manga.
   • Given answer: 妹はマンガばかり読んでいます。
   • My answer: 妹はマンガはばかり読んでいます。

Are those bolded particles allowed? Are they violating some rule I'm unware of? If they are allowed, why doesn't the answer key have them?

Bonus question My older sister does nothing but shop.

• Given answer: 姉は買い物ばかりしています。
• My answer: 姉は買い物をしてばかりいます。

Are these the same?

Answer 1

が and を are simple case particles. When they are used with nuanced particles such as しか, ばかり, も and さえ, these replace が/を. You must say just しか instead of がしか or しかが even if this marks a subject. They sometimes replace and sometimes follow に/へ. They never replace から/まで/etc.

• 自転車があります。 There are bikes.
• 自転車しかありません。 There are only bikes.
• 本を読みます。 I read a book.
• 本しか読みません。 I only read a book.
• 自転車に乗ります。 I ride a bike.
• 自転車(に)しか乗りません。 I only ride a bike.
• 学校へ行きます。
• 学校(へ)しか行きません。

• 妹はマンガを読んでいます。 My sister is reading manga.
• 妹はマンガばかり読んでいます。 My sister only reads manga.
• 妹はマンガに興味があります。 My sister is interested in manga.
• 妹はマンガにばかり興味があります。 My sister is interested only in manga.
• 男性から手紙をもらいます。 I receive letters from males.
• 男性からばかり手紙をもらいます。 I receive letters only from males.

Likewise, がばかり is ungrammatical, but ばかりが is fine. Each particle has exceptions you have to memorize eventually.

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食べいませんでした is plain ungrammatical. You probably wanted to say either 食べませんでした or 食べていませんでした.

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姉は買い物ばかりしています and 姉は買い物をしてばかりいます are both correct. They mean almost the same thing, but the former focuses on what she does, while the latter focuses on how she spends time.