Write the missing numbers in the sequence. 4/10

1 ten,    nine,    ,    seven
2 two,    four,    ,    eight
3 twenty,    nineteen,    eighteen,   
4 twenty,    thirty,    forty,    
5 fifty,    forty,    thirty,    ,    ten
6 five,    ten,    ,    twenty
7 two,    four,    eight,    sixteen,