Learners’ knowledge of their L1 helps them to learn the parts of the L2 that are similar to the L1.
The L1 may interact with learners’ developmental sequences of the L2.
“Avoidance” may be associated with learners’ perception that a feature in the L2 is distant and different from their L1.
Learners are usually aware that idiomatic or metaphorical uses of words are often unique to a particular language; therefore, L1 transfer of these uses seldom occurs.
When learners’ interlanguage form does not cause any difficulty in communicating meaning, they may find it difficult to get rid of it (i.e., fossilization).