She is known {#blank#}1{#/blank#} on the problem for many years.

{#blank#}1{#/blank#}, more and more new substances have been discovered in the past years.

Now, it is still hanging on the wall of my bedroom. {#blank#}1{#/blank#} I couldn't help thinking of my friend.

Behind the farm house{#blank#}1{#/blank#}.

The meeting room where we planned to hold the meeting {#blank#}1{#/blank#}. 

{#blank#}1{#/blank#} each night is important for people's health.