The best way to explore _______ countryside is on _______foot.
Neither Join nor I ______able to persuade Richard’s grandfather to attend the wedding.
My dictionary has disappeared. Who ________ have taken it?
I looked under ______ bed and found _____ book I lost last week.
--- How long are you staying?--- I don’t know. _____.
It is reported that large amounts of locusts(蝗虫) _____ in their activity in the north now.