Letter sequences

Find the fixed steps and build the next pair

提示Nothing is random — measure how the letters move, then carry the movement on.

为什么Each pair of letters moves by two constant steps at once — one between the pairs and one inside each pair. Work both out from the pairs you are shown.

Nothing — a sequence never wraps past Z back to A

提示This is where sequences differ from codes — no circle here, just a straight line of letters.

为什么Letter CODES wrap round (after Z comes A); letter sequences do not. If your rule forces a letter past Z, the rule is wrong — try a different step.

The first letters or the word lengths

提示Look at how each one starts — or count how long each is.

为什么Check the opening letters for a constant alphabet step; if that fails, check whether each word grows or shrinks by the same amount. One rule runs the whole series.

A fixed jump through the alphabet, the same for every pair

提示Measure the gap in a complete example — that distance holds all the way down.

为什么The step can run forwards or backwards. Work it out from the finished pairs, then complete the unfinished one.

Count the gap between two letters you are given

提示Use your alphabet line — how far is it from one to the next?

为什么Then check the same gap against the next pair too: a rule that only fits once is a guess, not a rule.

Forwards or backwards

提示Do not assume the letters climb — check which way the gap points.

为什么D then B could be a step of two back. If a forward rule will not fit, try the reverse before giving up.

Write the alphabet out and count along it

提示Put all 26 down on paper before the first question.

为什么Counting on fingers slips; a written line does not. Mark the letters you use so you can see the pattern taking shape.

That your rule fits every pair shown, not just the first

提示One match could be luck — the pattern must hold from start to finish.

为什么A step that works for the opening letters can still fail later on. Test the rule across everything you can see before you commit.

outer and inner

提示One step travels along the row; the other stays within a single pair.

为什么The two steps are separate rules. Find each on its own — muddling them together is the commonest slip in pair sequences.

No — only the jump inside each pair is fixed

提示Do not hunt for a rule that is not there — one measurement is all you need.

为什么That is the difference from letter sequences, where the opening letters do march in step. Read which type you are in before you start measuring.