read.table("target-genes.txt", header = TRUE, sep = "\t")Error in scan(file = file, what = what, sep = sep, quote = quote, dec = dec, : line 19 did not have 4 elements。这个报错要怎么解决啊，我查看过了文件的第19行没有问题啊。下面是文件部分内容：DrugMolIdIngredientsTargetsBaizhuMOL00002214-acetyl-12-senecioyl-2E,8Z,10E-atractylentriolProstaglandin G/H synthase 2BaizhuMOL000033(3S,8S,9S,10R,13R,14S,17R)-10,13-dimethyl-17-[(2R,5S)-5-propan-2-yloctan-2-yl]-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3-olProgesterone receptorBaizhuMOL0000493β-acetoxyatractyloneMuscarinic acetylcholine receptor M3BaizhuMOL0000493β-acetoxyatractyloneMuscarinic acetylcholine receptor M1cetoxyatractyloneAcetylcholinesteraseBaizhuMOL0000493β-acetoxyatractyloneDipeptidyl peptidase IVBaizhuMOL0000493β-acetoxyatractyloneNeuronal acetylcholine receptor protein, alpha-7 chainBaizhuMOL0000728β-ethoxy atractylenolide Ⅲ Prostaglandin G/H synthase 2BaizhuMOL0000728β-ethoxy atractylenolide Ⅲ Gamma-aminobutyric acid receptor subunit alpha-1