R, 85 bytes

for(i in seq(l<-strsplit(readLines(),"")))cat("if"(i%%2,`(`,rev)(l[[i]]),"\n",sep="") 

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Input from stdin and output to stdout.

R, 85 bytes

for(i in seq(l<-strsplit(readLines(),"")))cat("if"(i%%2,`(`,rev)(l[[i]]),"\n",sep="") 

Try it online!

Input from stdin and output to stdout.

Each line must be terminated by a linefeed/carriage return/CRLF, and it prints with a corresponding newline. So, inputs need to have a trailing linefeed.