Clara,

Its very difficult without seeing the puzzle. There are certainly no 'groups' in the three rows you have given us. Here would be my summary of the advanced strategies to think through.

Groups: as discussed previously in this forum, within any row, any column or any 3x3 block, looking for either a group of (say) three cells that only have some combination of three possible answers; or (say) three numbers that only fit (in some combination) into three cells. Groups of two are very common and usually easier to spot if you have any. Given any group you can eliminate other possibilities from your row/column/block as per the discussion above.

Restricted cells: This usually applies to a number that can only fit within one column or row within a particular 3x3 block. This means that this number cannot fit within this particular column or row in the neighbouring 3x3 blocks.

X-Wings, Swordfish etc: There are some more advanced strategies which I will be surprised you need to implement. X-wings are the most useful. This involves finding two rows that only have the same two 'column options' for a particular number e.g. in row one, 4 can only go in column three and seven and in row five, 4 can also only go in column three and seven. As there are only two options within both of these rows, if you place one of the numbers (say the 4 in R1C3) then that will automatically eliminate the possibility in the corresponding row (R5C3 in our example). This means that the number must go in the 'diagonal' cell (R5C7 becomes a 4 in the example). The number must go in both cells of one of the two diagonal pairs. This means that other cells in that column cannot possibly have that number (4) in them, thus eliminating some possibilities for you. Clearly, X wings also work if you find two columns that have the same two 'row options'. You can find examples with probably a better explanation here:

http://www.simes.clara.co.uk/programs/sudokutechnique6.htmSwordfish are an extension of X wings into three columns and three rows. I've done a lot of hard puzzles and never had to use one yet, even some of the puzzles listed on the swordfish page:

http://www.simes.clara.co.uk/programs/sudokutechnique7.htmHope that helps,

Andrew