问答题 If, therefore, we look at the speech and writing of the foreign language learner, there is little reason to doubt that we will find many mistakes which can be traced back to the mother tongue. The comedian probably gets most, though not all, of his effects by imitating the foreigner's pronunciation, but in fact evidence of the mother tongue is found on a far wider scale than this, even if it is not always recognized. It might be useful to begin this discussion by demonstrating the extent to which a learner uses features of his native language in his attempts to speak and write in the foreign language. It is necessary to figure out the effect one's mother tongue on the foreign language he is learning. If we imagine the efforts of a learner to produce the English sentence: His wife wants to pay her grandfather a visit in the old people's home, we should be able to see some of the substitutions from the mother-tongue that are made by different learners and that cause errors.