R中两张图做一个tif和三张图做一个tif的问题-经管之家官网！

1. 现在想把两个panels放在一个tif图上：
tiff(file=“myplot1.tif", width=144, height=72, units='mm', res=600, compression='lzw', pointsize=5)
par(mfrow=c(1, 2))
par(mar=c(6, 5, 2, 2))
boxplot( a.five~marks, cex.lab=2, cex.axis=2, xlab="",
ylab="", ylim=c(min(a.five, a0), a.upper), col="grey70",
names=c("OLS", expression(chi^2), expression(psi^2), "WLS", "MLE"), cex=2, las=3)
abline(h=a0, lty=2, col=2)
box()
par(mar=c(6, 5, 2, 2))
boxplot( b.five~marks, cex.lab=2, cex.axis=2, xlab="",
ylab="", ylim=c(min(b.five, b0), b.upper), col="grey70",
names=c("OLS", expression(chi^2), expression(psi^2), "WLS", "MLE"), cex=2, las=3)
abline(h=b0, lty=2, col=2)
box()
dev.off()
2. 而另外一个像把三个做在一幅tif图上：
tiff(file=“myplot2.tif", width=216, height=72, units='mm', res=600, compression='lzw', pointsize=5)
par(mfrow=c(1, 3))
par(mar=c(6, 5, 2, 2))
boxplot( ropt.four~marks, cex.lab=2, cex.axis=2, xlab="", ylab="",
ylim=c(min(ropt.four, ropt.val), ropt.upper), col="grey70",
names=c("OLS", expression(chi^2), expression(psi^2), "WLS"), cex=2, las=3)
abline(h=ropt.val, lty=2, col=2)
box()
par(mar=c(6, 5, 2, 2))
boxplot( topt.four~marks, cex.lab=2, cex.axis=2, xlab="", ylab="",
ylim=c(min(topt.four, topt.val), topt.upper), col="grey70",
names=c("OLS", expression(chi^2), expression(psi^2), "WLS"), cex=2, las=3)
abline(h=topt.val, lty=2, col=2)
box()
# win.graph()
par(mar=c(6, 5, 2, 2))
boxplot( tmax.four~marks, cex.lab=2, cex.axis=2, xlab="", ylab="",
ylim=c(min(tmax.four, tmax.val), tmax.upper), col="grey70",
names=c("OLS", expression(chi^2), expression(psi^2), "WLS"), cex=2, las=3)
abline(h=tmax.val, lty=2, col=2)
box()
dev.off()
结果发现做出的tif图上，坐标的xlab和ylab不一样大，十分恼人。有没有好的办法，是的图形显示的xlab和ylab的一样大小？是不是我设置的par(mar=c(6,5,2,2))出了问题，谢谢！