He tried his best to solve the problem,_____difficult it was. A however B. no matter C. whatever D. although
Ladies and gentlemen, please remain __________ until the plane has come to a complete stop.
We are invited to a party _________in our club next Friday.
_________ the right kind of training , these teenage soccer players may one day grew the international stars.
Nowadays people sometimes separate their waste to make it easier for it .
When he the door, he found his keys were nowhere.