i think the cause is proplem with grammar. English always deals with reference of time while Indonesian does not have one. Moreover, there are singular and piural forms that the students have to distinguish and still many form the have to be learned. Most student are very easy to get confused with English grammar, while gammar is very needed to form a right sentence. if the students do not have grammar masterry, of cause they will not be able to produce sentences that grammatically right. Realizing that the grammar students have is very weak, So they feel embarrassed when they want to produce English sentencees orally.