许多抗原称为胸腺依赖性抗原是因为( )。

听力原文：What differences are there between British English and American English？

What differences are there between British English and American English？

The differences involve grammar, ______, etc.

What differences are there between British English and American English？

The differences involve grammar, ______, etc.

are the differences between Chinese dressing manners and western ones？ 3. What are the differences between Chinese gift-giving manners and western ones？ 4. How to use chopsticks properly？ 5. What to wear in the formal occasions？

What is the purpose of mentioning the medical history of European royalty？

A．To confirm that inbreeding is not a good thing.

B．To compare gene differences between cats and humans.

C．To explain the definition of inbreeding.

D．To refute the traditional idea about inbreeding.

What is the talk mainly about？

A．The guild systems of ancient China and India.

B．The differences between early and modern guilds.

C．The function and organization of early guilds.

D．The method of advancement for guild members,