A. lack of research tools
B. lack of research funds
C. limited time of studies
D. limited size of samples
As oil and other fossil fuels become more costly and difficult to find, research
As oil and other fossil fuels become more costly and difficult to find, research
As oil and other fossil fuels become more costly and difficult to find, research
Writers find it difficult ___________________.Writers find it difficult ________
[试题]（49） In fact, it is difficult to see how journalists who do not have a clear preps of the basic features of the Canadian Constitution can do a competent job on political stories.
[试题]（49）In fact, it is difficult to see how journalists who do not have a clear preps of the basic features of the Canadian Constitution can do a competent job on political stories.此处译文为：
[单选题]The work is so difficult that they don’t know ( ).A.to do itB.what to do it
It is also very difficult to make transportation construction on the surface of
It is also very difficult to make transportation construction on the surface of
[单选题]H．ow did the host find out there was a thief in the house?A． He heard someone breathing.B． He heard footsteps in the hall.C． He noticed a shadow on the floor.D． He noticed that his gifts were gone.