Error Linear Regression with missing data

Question

I\'ve got a dataset like this:

dat1 <- read.table(header=TRUE, text="
Var1 Var2 Var3 Var4 Var5 Var6 Var7 Var8 Var9
3.571429 2.8 5 6 2.5 3.3 2.4 2 2.7