1.upon receipt 一旦收到

Quotations and samples will be sent upon receipt of your specific enquires.
一收到你方的具体询盘，我方将马上寄送上报价和样品。

Establishment of service is reliant upon receipt by the Company of payment of affirmed charges.
建立服务是依赖于收到该公司支付的费用肯定。

Order may only be processed upon receipt of full payment and refund will not be accepted in any cases.
本公司只处理已收妥所有款项的订单，并在任何情况之下都不接受退款。

2.L/C abbr. 信用状（letter of credit）

An irrevocable and transferable L/C.
不可撤销的，可转让的信用证。

As for payment, we prefer an irrevocable L/C.
至于付款条件，我方希望开立不可撤销的信用证。

For large orders, we insist on payment by L/C.
对于金额大的订货，我们便要求开信用证。

3.rather difficult 相当困难

To be a good engineer is rather difficult.
要做一个好的工程师是相当困难的。

I found her rather difficult to work with .
我发现很难和她共事。

This book is easy, but that one is rather difficult.
这本书容易读懂，但那本很难读。

4.out of stock adv. 已脱销

These boots are out of stock right now.
这双靴子目前缺货。

Sorry, king sized shirt is out of stock now.
不好意思，大号的衬衫现在没货。

This item is out of stock, but it is on order.
这项产品全部售空（已无存货），但已经订购了。