I enjoy using Facebook because I could see photos of my friends there.
Students are often confused about can/could, will/would. Sometimes they have learned at school that could and would are more formal, or more polite than can and will. That may be true when you are requesting something, but in IELTS speaking and writing you’re usually using can and will to communicate possibility or ability rather than to make a request.
In this case there is a strong possibility (almost 100%) that I will see my friend’s photos on Facebook. In this case I need to use can.
Let’s imagine a similar situation where there is no possibility:
Here the writer clearly does not have an Internet connection and so he is not likely to see his friend’s photos. Notice that in this example could is part of a structure called ‘second conditional’, which is used to describe an unlikely situation in the present:
If + subj + V2 + ‘,’ + subj + could/would + V1
In the ‘second conditional’ the situation you are describing is unlikely:
This kind of imaginary situation is by far the most common context for could and would.
Indonesian students tend to overuse ‘will‘ because they want to translate ‘akan‘. But ‘will‘ is not used in English as much as ‘akan’ is used in Indonesian. Actually there are generally only three situations where will is suitable:
Look at those clouds. I forgot my umbrella. If it rains I will get wet!
Look at those dark clouds! It will probably rain soon.
He drives me crazy. He‘ll (he will) trim his nails and then leave the cuttings all over the floor for me to clean up!
It’s unusual to talk about past abilities, because once you acquire an ability, for example the ability to swim, you rarely lose that ability. It would be ridiculous, for example, to write:
We generally only lose this kind of ability when something terrible happens to us:
On the other hand ability can sometimes be a matter of degree. For example, we can talk about partial ability, or about changes in our level of ability:
Most of the time when we talk about ability we use can – present tense – because, most of the time, we’re making a claim that is true now or always.
Next time you write could or would stop and think. You probably should be writing can or will!