關于環(huán)保材料的研發(fā)和綠色包裝設計的主要目標是開發(fā)出既能保護環(huán)境又能滿足客戶需求的產品。這可能涉及到使用可再生資源，減少能源消耗，以及提高產品的耐用性和可回收性等。

```php

if ($timestamp > $timestamp) {

echo "$timestamp is greater than $timestamp";

} elseif ($timestamp < $timestamp) {

echo "$timestamp is less than $timestamp";

} else {

echo "$timestamp is equal to $timestamp";

}

```