Mark 16: 16-17 is to the Apostles, not to us two thousand years later. Read Romans 1:8, about the great Commision it was already completed by them the Apostles before they died.
Romans 1:8
First, I thank my God through Jesus Christ for you all, that your faith is spoken of throughout the whole world.
Romans 10:18
But I say, Have they not heard? Yes verily, their sound went into all the earth, and their words unto the ends of the world.(Romans 16:25-26)
“...My gospel... has been made manifest, and by the prophetic Scriptures has been made known to all nations (Greek ethnos)...”
Acts 17:6
And when they found them not, they drew Jason and certain brethren unto the rulers of the city, crying, These that have turned the world upside down are come hither also;
Colo 1:5-6
For the hope which is laid up for you in heaven, whereof ye heard before in the word of the truth of the gospel;
6 Which is come unto you, as it is in all the world; and bringeth forth fruit, as it doth also in you, since the day ye heard of it, and knew the grace of God in truth:
Colo 1:23
If you continue in the faith grounded and settled, and benot moved away from the hope of the Gospel and which was preached to every creature which is under Heaven; where of I Paul am made a minister.
You also should read Isaiah 28 so you will come to find out that the gift of tongues was to judge Israel as it did in 30 AD till the judgment that happened to them in 70 AD. After that time Tongues is not needed. It was a foundational gift that came to its ened when the foundation was completed with the death of the last Apostle John.
Now that the foundation was laid there is no use for it today.
Jesus also told the Disciples that He would come before they would die in Matt 16:28, Matt 10:23 and also told Caiaphas the priest that He would see Jesus coming in the His kingdom in the clouds of the air. If Caiaphas didnt see Christs coming it would make Jesus a lyer. Jesus cant lie and didnt. He cam in 70 AD and fulfilled matt 24 not one stone was left upon another. Evebn Johns REV says that those who periced Him would see Him in Rev 1:7. God Bless rcscrolls@aol.com