I try to understand ________ that prevents so many Chinese from being as happy as one might expect．

A．why is it

B．what is it

C．why it is

D．what it is

Some experts think the wolf's team spirit for survival is ________ is needed in today's competitive culture．

A．that

B．what

C．which

D．how

China began selling tickets for the Wuhan-Guangzhou high-speed railway, ________ boasts the world's fastest train journey with a 350km per hour average speed．

A．which

B．that

C．it

D．what

In the UK, what impressed exchange students most was the Student Activity, ________ they could get lots of information outside．

A．where

B．that

C．which

D．when

The second runway of Hong Kong International Airport was officially ________ on May 26, 1990．

A．put into effect

B．made use of

C．taken notice of

D．put into use

We are sparing no efforts to create ________ more peaceful and more advanced world, ________ place where everyone enjoys his life and freedom．

A．the; a

B．/; the

C．a; a

D．the; the

Mrs Obama introduced the Let's Move ________ , whose goal is to reduce childhood obesity．(肥胖)

A．challenge

B．conflict

C．campaign

D．consequence

During the job interview, Bob was asked several questions, but he could answer ________ of them．

A．no one

B．nothing

C．none

D．neither

After the earthquake ，the electricity supply failed, ________ the cooling system break down．

A．having made

B．making

C．made

D．to make

The factory produces half a million pairs of shoes every year, 80％ ________ are sold abroad．

A．of which

B．which of

C．of them

D．of that