Why do students have difficulties in understanding

单项选择题

Questions 11-13 are based on the following talk. You now have 15 seconds to read Questions 11 - 13.

Why do students have difficulties in understanding English speech

A．Because they had very little chance to hear authentic English before.
B．Because they have a limited vocabulary.
C．Because they find it hard to pronounce English words correctly.
D．Because they are especially weak in listening and speakin