New Revised Standard Version
They asked him, “Teacher, when will this be, and what will be the sign that this is about to take place?”

Contemporary English Version
Some people asked, "Teacher, when will all this happen? How can we know when these things are about to take place?"

New American Bible
Then they asked him, “Teacher, when will this happen? And what sign will there be when all these things are about to happen?”

Douay-Rheims Bible
And they asked him, saying: Master, when shall these things be? And what shall be the sign when they shall begin to come to pass?

And they asked him, saying: Master, when shall these things be? And what shall be the sign when they shall begin to come to pass?

when.

Luke 21:32 Amen, I say to you, this generation shall not pass away till all things be fulfilled.

Daniel 12:6,8 And I said to the man that was clothed in linen, that stood upon the waters of the river: How long shall it be to the end of these wonders? . . .

Matthew 24:3 And when he was sitting on mount Olivet, the disciples came to him privately, saying: Tell us when shall these things be? And what shall be the sign of thy coming and of the consummation of the world?

Mark 13:3,4 And as he sat on the mount of Olivet over against the temple, Peter and James and John and Andrew asked him apart: . . .

John 21:21,22 Him therefore when Peter had seen, he saith to Jesus: Lord, and what shall this man do? . . .

Acts 1:6,7 They therefore who were come together, asked him, saying: Lord, wilt thou at this time restore again the kingdom of Israel? . . .

what.

Luke 21:20,21,27,28 And when you shall see Jerusalem compassed about with an army, then know that the desolation thereof is at hand. . . .

Matthew 24:15,16 When therefore you shall see the abomination of desolation, which was spoken of by Daniel the prophet, standing in the holy place: he that readeth let him understand. . . .

Mark 13:14 And when you shall see the abomination of desolation, standing where it ought not (he that readeth let him understand): then let them that are in Judea flee unto the mountains.