2 . These days, teachers have been sparing no efforts to create         they hope will be the best means to improve the efficiency of online teaching,         some students don’t notice or care about, though.

A．that, which

B．what, which

C．which, what

D．what, that

3 . China will allow all couples to have three children, ________, in my opinion, is helpful to cope with the increasingly aging society.

A．that

B．which

C．what

D．who

4 . People sit uncomfortably on plastic chairs, reading   old magazines, ________ _have been read hundreds of times previously.

A．all of them

B．all of which

C．each of them

D．each of which

6 . ________ is widely accepted, in the Middle East Arabs greet each other by touching noses, but this is not a polite way of greeting in other cultures.

A．As

B．It

C．Which

D．What

8 . After a 57-day hiking, the explorers finally reached a place, ________ they believed was the South Pole.

A．which

B．where

C．that

D．as

9 . Inspired by dolphins, people have learnt how to send signals underwater, ______ is currently employed in tsunami early-warning systems.

A．which

B．that

C．who

D．what