There are several and this is the first one I will post in this thread.

The seven trumpet angels, have they sounded yet?  A quote frim EGW at the end,

Read these scriptures and see after the sixth trumpet angel it tells us these are plagues, so we can know these are the first seven plagues just before the seven last plagues,

Re 9:14 Saying to the sixth angel which had the trumpet, Loose the four angels which are bound in the great river Euphrates.
Re 9:15 And the four angels were loosed, which were prepared for an hour, and a day, and a month, and a year, for to slay the third part of men.
Re 9:16 And the number of the army of the horsemen were two hundred thousand thousand: and I heard the number of them.
Re 9:17 And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.
Re 9:18 By these three was the third part of men killed, by the fire, and by the smoke, and by the brimstone, which issued out of their mouths.
Re 9:19 For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt.
Re 9:20 And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk:
Re 10:7 But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets.
Re 11:15 And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.

Now notice of this verse that it intimates, leads one to know there was 7 first,

Re 15:1 ¶ And I saw another sign in heaven, great and marvellous, seven angels having the seven last plagues; for in them is filled up the wrath of God.

Another thing is the trumpet angels cannot start until Jesus comes and gives them the signal to start!

Re 8:3 And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne.

Now we should know who that is ministering at the altar, Jesus our High Priest of course!

Re 8:4 And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel's hand.
Re 8:5 And the angel took the censer, and filled it with fire of the altar, and cast it into the earth: and there were voices, and thunderings, and lightnings, and an earthquake.
Re 8:6 And the seven angels which had the seven trumpets prepared themselves to sound.
Re 8:7 ¶ The first angel sounded, and there followed hail and fire mingled with blood, and they were cast upon the earth: and the third part of trees was burnt up, and all green grass was burnt up.

Now when in history was ever a third of the trees burned up and ALL the green grass?

No trumpet angel has sounded yet, PERIOD! 

The power of the Holy Ghost must be upon us, and the Captain of the Lord's host will stand at the head of the angels of heaven to direct the battle. Solemn events before us are yet to transpire. Trumpet after trumpet is to be sounded, vial after vial poured out one after another upon the inhabitants of the earth.  {14MR 287.1}

1Jo 4:4 ¶ Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world.