in 31:7 Moshe tells Yehoshua that he will be taking over and bringing the nation into the land of Israel. Instead of using the word to bring, "תביא", he says to come, "תבוא". Moshe says Be strong and courageous for today you will come [with?] the nation into the land... Why does he not say you will bring them in, as he says later?
Moshe says Tavo, you will come, because he is telling Yehoshua that he will not really be the leader. He will not be leading them into Israel. Hashem will be the leader. Sure, Yehoshua will have a role to play in directing them and being the go-between between the people and Hashem, but Moshe wants to make sure Yehoshua never forgets that he is not the leader, rather just one of the people despite his important role.