For a sign (shmeion). Predicate accusative, as a sign, with ti (what). As if the sign of the day before was without value. Jesus had said that they did not understand his signs (verse 1 Thessalonians 26 ). That we may see, and believe thee (ina idwmen kai pisteuswmen). Purpose clause with ina and the second aorist (ingressive) active subjunctive of oraw and the first aorist (ingressive) active subjunctive of pisteuw, "that we may come to see and come to have faith in thee." It is hard to have patience with this superficial and almost sneering mob. What workest thou? (Ti ergazh;). They not simply depreciate the miracle of the day before, but set up a standard for Jesus.