-Phrasal verbs - Phrasal verbs in English can cause difficulties for many learners because they have several meanings and different syntactic patterns.There are also a number of phrasal verb differences between American and British English.
Word derivation - Word derivation in English requires a lot of rote learning.For example,an adjective can be negated by using the prefix un- (e.g.unable),in- (e.g.inappropriate),dis- (e.g.dishonest),or a- (e.g.amoral),or through the use of one of a myriad of related but rarer prefixes,all modified versions of the first four.
Size of lexicon - The history of English has resulted in a very large vocabulary,essentially one stream from Old English and one from the Norman infusion of Latin-derived terms.(Schmitt & Marsden claim that English has one of the largest vocabularies of any known language.) This inevitably requires more work for a learner to master the language.
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