VHDL惯性延时和传输延时的问题

[ChuanjieZhu]

（1）S<= 3 after 1 ns,5 after 3 ns,7 after 5 ns;
（2）
S<= 3 after 1 ns;
S<= 5 after 3 ns;
S<= 7 after 5 ns;
第一中寫法和第二中寫法有什麽區別？

rx_data<=transport 11 after 10 ns;
rx_data<=transport 20 after 22 ns;
rx_data<=transport 35 after 18 ns;
这里的20会不会赋给rx_data,为什么？