Hark! hark! -what was that? Hark! hark to the shout!

听！你听！——那是什么声音？听！听那个响声！

Clinical trials of pluripotent cells are already happening, though they hark back to the days when only cells derived from embryos were available.

多能细胞的临床试验其实早已开始进行，只是这种多能细胞还是由胚胎干细胞所培养（这在当时也是唯一可用的技术）。