Why do people say English is the hardest language to learn?
Mainly because of grammar...
Probably because there are so many words that have more than one meaning despite their identical pronunciation. For example,
Bear and bare.
Two, too and to.
'They were too close to the door to close it.'
Grammar is also another reason why English is one of the hardest languages to learn. For example,
'After a number of injections, my jaw got number.'
Here the word number and number are identical, but they mean two different things and are pronounced differently. Another way of writing this could be:
'After numerous injections, my jaw got numb.'
'After numerous injections, my jaw got number.'
'After a number of injections, my jaw got more numb.'
This, however, is not grammatically correct to place a comparative before the adjective. You are either numb or not numb at all. On the other hand, people still speak this way as it 'sounds' reasonable and it can often help with emphasis.