This tesuji has to be somewhere on this site, but I can't find it -- and I always forget it!
(;AB[ii]AB[ih]AB[ki]AB[kj]AB[kk]AW[ji]AW[jh]AW[kh]AW[lh]AW[kf]AB[ig]C[White just played the marked stone. How can black connect?]TR[ji]AB[gh]AB[ll]AB[gi]AW[gj]AW[fj]AP[goproblems]
(;B[ik]
(;W[jj]
(;B[hl]C[Great job!RIGHT])
(;B[ij];W[jk];B[jl];W[il]
(;B[im];W[hl])
(;B[hl];W[im])
(;B[hm];W[hl]))
(;B[jk];W[ij];B[hj];W[hk]))
(;W[ij]
(;B[hj];W[jj]
(;B[hl]C[RIGHT])
(;B[hk];W[jk];B[jl];W[il]C[In some cases, J8 may not work for white, but without contet, don't leave the connection to chance!]))
(;B[jj];W[hj])))
(;B[jj];W[ij]
(;B[ik];W[hj])
(;B[hj];W[ik])
(;B[hk];W[hj]))
(;B[ij];W[jj]
(;B[jk];W[ik]
(;B[il];W[hk])
(;B[hk];W[il])
(;B[hl];W[hk]))
(;B[ik];W[jk];B[jl];W[il]
(;B[hl];W[im])
(;B[im];W[hl])
(;B[hm];W[hl])))
(;B[hk];W[jj]
(;B[jk];W[ij];B[hj];W[ik];B[il];W[hl]
(;B[gm];W[gl])
(;B[hm];W[gl])
(;B[gl];W[hm]))
(;B[ik];W[jk];B[jl];W[il]
(;B[hm];W[im];B[in];W[jm])
(;B[im]C[A ladder is not good enough.];W[hl])
(;B[hl];W[im]))
(;B[ij];W[jk];B[jl];W[ik]
(;B[il];W[hj])
(;B[hj];W[il]))
(;B[hj];W[jk];B[jl];W[il]
(;B[ik];W[im])
(;B[hl];W[im]))))