We won't know whether it will be successful. We won't know whether there will be good _____.
The doctor suggested he ______.
They are considering______ they should do the experiment .
Lincoln, ______ President of ______ United States, was assasinated(暗杀)on April 14th , 1865 .
Why ______ a bad idea to ask Amy for advice?
Which is ______ country, Canada or Australia?