It's very difficult to concentrate ___ prepositions! Which word completes the sentence?

It's very difficult to concentrate ___ prepositions! Which word completes the sentence?

• A. On
• B. In
• C. At
• D. To

Answer: (A)

Directing mental effort toward something is shown with the verb concentrate followed by on. In English, the common way to say you’re focusing your attention is to use concentrate on something. So the sentence means it’s hard to focus your attention on prepositions, which is why on is the natural choice. For example: I need to concentrate on my grammar; she finds it difficult to concentrate on the lesson. This pattern uses on to mark the object of your concentration. The other prepositions don’t fit because they don’t convey the idea of directing attention in this verb phrase. Concentrate in is used for different senses (like something concentrated inside a place or substance), concentrate at isn’t a standard way to express focusing, and concentrate to isn’t used to indicate what you’re focusing on.

Directing mental effort toward something is shown with the verb concentrate followed by on. In English, the common way to say you’re focusing your attention is to use concentrate on something. So the sentence means it’s hard to focus your attention on prepositions, which is why on is the natural choice.

For example: I need to concentrate on my grammar; she finds it difficult to concentrate on the lesson. This pattern uses on to mark the object of your concentration.

The other prepositions don’t fit because they don’t convey the idea of directing attention in this verb phrase. Concentrate in is used for different senses (like something concentrated inside a place or substance), concentrate at isn’t a standard way to express focusing, and concentrate to isn’t used to indicate what you’re focusing on.