[未知用户] 你应该是有些命令打错了，比如
col=(3,4)应该是
col = c(3, 4)，
cex.main=1,1应该是
cex.main = 1.1等等。
完整的程序在下面：
x = seq(-pi, pi, len = 65);
plot(x, sin(x), type = "l", ylim = c(-1.2, 1.8),
col = 3, lty = 2);
points(x, cos(x), pch = 3, col = 4);
add.layer("title");
title("This is the title", cex.main = 1.1);
add.layer("legend");
legend(-1, 1.9, c("sin", "cos"), col = c(3, 4),
text.col = "green4", lty = c(2, -1),
pch = c(-1, 3), merge = TRUE, bg = "gray90");
